├── .gitignore
├── .vscode
    ├── settings.json
    └── launch.json
├── .settings
    ├── org.eclipse.jdt.apt.core.prefs
    ├── org.eclipse.m2e.core.prefs
    ├── org.eclipse.core.resources.prefs
    └── org.eclipse.jdt.core.prefs
├── src
    └── main
    │   └── java
    │       └── bistu
    │           ├── share
    │               ├── Instruction.java
    │               ├── Overview.java
    │               └── Detail.java
    │           ├── server
    │               ├── MainServer.java
    │               └── Serve.java
    │           └── db
    │               └── DbUtil.java
├── .project
├── DbStructure
    └── createDb.sql
├── .classpath
└── pom.xml


/.gitignore:
--------------------------------------------------------------------------------
1 | /target/*
2 | /**/*.class
3 | 


--------------------------------------------------------------------------------
/.vscode/settings.json:
--------------------------------------------------------------------------------
1 | {
2 |     "java.configuration.updateBuildConfiguration": "automatic"
3 | }


--------------------------------------------------------------------------------
/.settings/org.eclipse.jdt.apt.core.prefs:
--------------------------------------------------------------------------------
1 | eclipse.preferences.version=1
2 | org.eclipse.jdt.apt.aptEnabled=false
3 | 


--------------------------------------------------------------------------------
/.settings/org.eclipse.m2e.core.prefs:
--------------------------------------------------------------------------------
1 | activeProfiles=
2 | eclipse.preferences.version=1
3 | resolveWorkspaceProjects=true
4 | version=1
5 | 


--------------------------------------------------------------------------------
/.settings/org.eclipse.core.resources.prefs:
--------------------------------------------------------------------------------
1 | eclipse.preferences.version=1
2 | encoding//src/main/java=UTF-8
3 | encoding//src/test/java=UTF-8
4 | encoding/<project>=UTF-8
5 | 


--------------------------------------------------------------------------------
/src/main/java/bistu/share/Instruction.java:
--------------------------------------------------------------------------------
 1 | package bistu.share;
 2 | 
 3 | public class Instruction {
 4 |     public static final int SERVE_END = 999;
 5 |     public static final int GET_LIST = 1;
 6 |     public static final int GET_DETAIL = 2;
 7 |     public static final int UPDATE_STICKY = 3;
 8 |     public static final int REMOVE_STICKY = 4;
 9 |     public static final int ADD_STICKY = 5;
10 | 
11 |     public static final int ERR_CODE = -1;
12 |     public static final int FINE_CODE = 0;
13 | }


--------------------------------------------------------------------------------
/.settings/org.eclipse.jdt.core.prefs:
--------------------------------------------------------------------------------
 1 | eclipse.preferences.version=1
 2 | org.eclipse.jdt.core.compiler.codegen.targetPlatform=11
 3 | org.eclipse.jdt.core.compiler.compliance=11
 4 | org.eclipse.jdt.core.compiler.problem.enablePreviewFeatures=disabled
 5 | org.eclipse.jdt.core.compiler.problem.forbiddenReference=warning
 6 | org.eclipse.jdt.core.compiler.problem.reportPreviewFeatures=ignore
 7 | org.eclipse.jdt.core.compiler.processAnnotations=disabled
 8 | org.eclipse.jdt.core.compiler.release=disabled
 9 | org.eclipse.jdt.core.compiler.source=11
10 | 


--------------------------------------------------------------------------------
/.project:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <projectDescription>
 3 | 	<name>sticky-server</name>
 4 | 	<comment></comment>
 5 | 	<projects>
 6 | 	</projects>
 7 | 	<buildSpec>
 8 | 		<buildCommand>
 9 | 			<name>org.eclipse.jdt.core.javabuilder</name>
10 | 			<arguments>
11 | 			</arguments>
12 | 		</buildCommand>
13 | 		<buildCommand>
14 | 			<name>org.eclipse.m2e.core.maven2Builder</name>
15 | 			<arguments>
16 | 			</arguments>
17 | 		</buildCommand>
18 | 	</buildSpec>
19 | 	<natures>
20 | 		<nature>org.eclipse.jdt.core.javanature</nature>
21 | 		<nature>org.eclipse.m2e.core.maven2Nature</nature>
22 | 	</natures>
23 | </projectDescription>
24 | 


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/DbStructure/createDb.sql:
--------------------------------------------------------------------------------
 1 | CREATE DATABASE db_sticky_android;
 2 | 
 3 | DROP TABLE IF EXISTS `sticky`;
 4 | 
 5 | CREATE TABLE `sticky` (
 6 |   `c_id` int(11) NOT NULL AUTO_INCREMENT,
 7 |   `c_modify` datetime NOT NULL,
 8 |   `c_overview` varchar(300) DEFAULT NULL,
 9 |   `c_full_text` mediumtext DEFAULT NULL,
10 |   PRIMARY KEY (`c_id`)
11 | );
12 | 
13 | CREATE TRIGGER t_modify_overview_insert
14 |     BEFORE INSERT ON db_sticky_android.sticky FOR EACH ROW
15 |         SET NEW.c_overview = SUBSTRING(NEW.c_full_text, 1, 300)
16 | 
17 | CREATE TRIGGER t_modify_overview_update
18 |     BEFORE UPDATE ON db_sticky_android.sticky FOR EACH ROW
19 |         SET NEW.c_overview = SUBSTRING(NEW.c_full_text, 1, 300);


--------------------------------------------------------------------------------
/.vscode/launch.json:
--------------------------------------------------------------------------------
 1 | {
 2 |     // Use IntelliSense to learn about possible attributes.
 3 |     // Hover to view descriptions of existing attributes.
 4 |     // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
 5 |     "version": "0.2.0",
 6 |     "configurations": [
 7 |         {
 8 |             "type": "java",
 9 |             "name": "Debug (Launch) - Current File",
10 |             "request": "launch",
11 |             "mainClass": "${file}"
12 |         },
13 |         {
14 |             "type": "java",
15 |             "name": "Debug (Launch)-App<sticky-server>",
16 |             "request": "launch",
17 |             "mainClass": "bistu.App",
18 |             "projectName": "sticky-server"
19 |         }
20 |     ]
21 | }


--------------------------------------------------------------------------------
/src/main/java/bistu/share/Overview.java:
--------------------------------------------------------------------------------
 1 | package bistu.share;
 2 | 
 3 | import java.io.Serializable;
 4 | import java.sql.Timestamp;
 5 | 
 6 | public class Overview implements Serializable {
 7 |     private long id;
 8 |     private Timestamp modifyTime;
 9 |     private String summary;
10 | 
11 |     public Overview(long id, Timestamp modifyTime, String summary) {
12 |         this.id = id;
13 |         this.modifyTime = modifyTime;
14 |         this.summary = summary;
15 |     }
16 | 
17 |     public long getId() { return id; }
18 |     public void setId(long id) { this.id = id; }
19 | 
20 |     public Timestamp getModifyTime() { return modifyTime; } 
21 |     public void setModifyTime(Timestamp modifyTime) { this.modifyTime = modifyTime; } 
22 | 
23 |     public String getSummary() { return summary; }
24 |     public void setSummary(String summary) { this.summary = summary; }
25 |     
26 |     @Override
27 |     public String toString() {
28 |         return String.format("Overview: id=%ld, modifyTime=%s, summary=%s", id, modifyTime.toString(), summary);
29 |     }
30 | 
31 | }


--------------------------------------------------------------------------------
/src/main/java/bistu/share/Detail.java:
--------------------------------------------------------------------------------
 1 | package bistu.share;
 2 | 
 3 | import java.io.Serializable;
 4 | import java.sql.Timestamp;
 5 | 
 6 | public class Detail implements Serializable {
 7 |     private long id;
 8 |     private Timestamp modifyTime;
 9 |     private String fullText;
10 | 
11 |     public Detail(long id, Timestamp modifyTime, String fullText) {
12 |         this.id = id;
13 |         this.modifyTime = modifyTime;
14 |         this.fullText = fullText;
15 |     }
16 | 
17 |     public long getId() { return id; }
18 |     public void setId(long id) { this.id = id; }
19 | 
20 |     public Timestamp getModifyTime() { return modifyTime; }
21 |     public void setModifyTime(Timestamp modifyTime) { this.modifyTime = modifyTime; }
22 | 
23 |     public String getFullText() { return fullText; }
24 |     public void setFullText(String fullText) { this.fullText = fullText; }
25 | 
26 |     @Override
27 |     public String toString() {
28 |         return String.format("Detail: id=%d, modifyTime=%s, fullText=%s", this.id, modifyTime.toString(), fullText);
29 |     }
30 |     
31 | }


--------------------------------------------------------------------------------
/.classpath:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | <classpath>
 3 | 	<classpathentry kind="src" output="target/classes" path="src/main/java">
 4 | 		<attributes>
 5 | 			<attribute name="optional" value="true"/>
 6 | 			<attribute name="maven.pomderived" value="true"/>
 7 | 		</attributes>
 8 | 	</classpathentry>
 9 | 	<classpathentry kind="src" output="target/test-classes" path="src/test/java">
10 | 		<attributes>
11 | 			<attribute name="optional" value="true"/>
12 | 			<attribute name="maven.pomderived" value="true"/>
13 | 			<attribute name="test" value="true"/>
14 | 		</attributes>
15 | 	</classpathentry>
16 | 	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-11">
17 | 		<attributes>
18 | 			<attribute name="maven.pomderived" value="true"/>
19 | 		</attributes>
20 | 	</classpathentry>
21 | 	<classpathentry kind="con" path="org.eclipse.m2e.MAVEN2_CLASSPATH_CONTAINER">
22 | 		<attributes>
23 | 			<attribute name="maven.pomderived" value="true"/>
24 | 		</attributes>
25 | 	</classpathentry>
26 | 	<classpathentry kind="src" path="target/generated-sources/annotations">
27 | 		<attributes>
28 | 			<attribute name="optional" value="true"/>
29 | 			<attribute name="maven.pomderived" value="true"/>
30 | 			<attribute name="ignore_optional_problems" value="true"/>
31 | 			<attribute name="m2e-apt" value="true"/>
32 | 		</attributes>
33 | 	</classpathentry>
34 | 	<classpathentry kind="src" output="target/test-classes" path="target/generated-test-sources/test-annotations">
35 | 		<attributes>
36 | 			<attribute name="optional" value="true"/>
37 | 			<attribute name="maven.pomderived" value="true"/>
38 | 			<attribute name="ignore_optional_problems" value="true"/>
39 | 			<attribute name="m2e-apt" value="true"/>
40 | 			<attribute name="test" value="true"/>
41 | 		</attributes>
42 | 	</classpathentry>
43 | 	<classpathentry kind="output" path="target/classes"/>
44 | </classpath>
45 | 


--------------------------------------------------------------------------------
/src/main/java/bistu/server/MainServer.java:
--------------------------------------------------------------------------------
 1 | package bistu.server;
 2 | 
 3 | import java.io.IOException;
 4 | import java.util.logging.Level;
 5 | import java.util.logging.Logger;
 6 | import java.net.ServerSocket;
 7 | import java.net.Socket;
 8 | 
 9 | import bistu.db.DbUtil;
10 | 
11 | public class MainServer {
12 | 
13 |     private static final String LOGGER_NAME = "sticky_android server";
14 |     private static final int SERVE_PORT = 12345;
15 | 
16 |     private Logger logger;
17 |     private ServerSocket ssocket;
18 | 
19 |     private Throwable loadJdbcDriver() {
20 |         Throwable t = null;
21 |         try {
22 |             Class.forName("org.mariadb.jdbc.Driver");
23 |         } catch (ClassNotFoundException e) {
24 |             t = e;
25 |         }
26 |         return t;
27 |     }
28 | 
29 |     private Throwable initServerSocket() {
30 |         Throwable t = null;
31 |         try {
32 |             this.ssocket = new ServerSocket(SERVE_PORT);
33 |             logger.log(Level.INFO, String.format("Listening port: %d", SERVE_PORT));
34 |         } catch (IOException e) {
35 |             t = e;
36 |         }
37 |         return t;
38 |     }
39 | 
40 |     private void serve() {
41 |         while (true) {
42 |             try {
43 |                 logger.log(Level.INFO, "waitting for user connecting...");
44 |                 Socket socket = this.ssocket.accept();
45 |                 new Thread(new Serve(socket)).start();
46 |             } catch (IOException e) {
47 |                 logger.log(Level.SEVERE, "there is a connection failed, relistening the same port.", e);
48 |             }
49 |         }
50 |     }
51 | 
52 |     private void initServer() {
53 |         this.logger = Logger.getLogger(LOGGER_NAME);
54 |         logger.log(Level.INFO, "inited the logger.");
55 | 
56 |         Throwable loadJdbcDriverThrow = this.loadJdbcDriver();
57 |         if (loadJdbcDriverThrow == null) {
58 |             logger.log(Level.INFO, "load the jdbc driver.");
59 |         } else {
60 |             logger.log(Level.SEVERE, "load jdbc drive error!", loadJdbcDriverThrow);
61 |             System.exit(-1);
62 |         }
63 | 
64 |         logger.log(Level.INFO, "initializing DbUtil...");
65 |         DbUtil.getInstance();
66 |         logger.log(Level.INFO, "initialize DbUtil succeed.");
67 | 
68 |         Throwable initServerSocketThrow = this.initServerSocket();
69 |         if (initServerSocketThrow == null) {
70 |             logger.log(Level.INFO, "inited the server socket.");
71 |         } else {
72 |             logger.log(Level.SEVERE, "init server socket error!", initServerSocketThrow);
73 |             System.exit(-1);
74 |         }
75 | 
76 |         logger.log(Level.INFO, "server start successfully.");
77 |         logger.log(Level.INFO, "start listen from user.");
78 |         this.serve();
79 | 
80 |     }
81 | 
82 |     public static void main(String[] args) {
83 |         MainServer s = new MainServer();
84 |         s.initServer();
85 |     }
86 | 
87 | }


--------------------------------------------------------------------------------
/pom.xml:
--------------------------------------------------------------------------------
 1 | <?xml version="1.0" encoding="UTF-8"?>
 2 | 
 3 | <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4 |   xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5 |   <modelVersion>4.0.0</modelVersion>
 6 | 
 7 |   <groupId>bistu</groupId>
 8 |   <artifactId>sticky-server</artifactId>
 9 |   <version>1.0-SNAPSHOT</version>
10 | 
11 |   <name>sticky-server</name>
12 |   <!-- FIXME change it to the project's website -->
13 |   <url>http://www.example.com</url>
14 | 
15 |   <properties>
16 |     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
17 |     <maven.compiler.source>11</maven.compiler.source>
18 |     <maven.compiler.target>11</maven.compiler.target>
19 |   </properties>
20 | 
21 |   <dependencies>
22 |     <dependency>
23 |       <groupId>junit</groupId>
24 |       <artifactId>junit</artifactId>
25 |       <version>4.13.1</version>
26 |       <scope>test</scope>
27 |     </dependency>
28 | 
29 |     <!-- https://mvnrepository.com/artifact/org.mariadb.jdbc/mariadb-java-client -->
30 |     <dependency>
31 |       <groupId>org.mariadb.jdbc</groupId>
32 |       <artifactId>mariadb-java-client</artifactId>
33 |       <version>2.5.2</version>
34 |     </dependency>
35 |   </dependencies>
36 | 
37 |   <build>
38 |     <pluginManagement><!-- lock down plugins versions to avoid using Maven defaults (may be moved to parent pom) -->
39 |       <plugins>
40 |         <!-- clean lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#clean_Lifecycle -->
41 |         <plugin>
42 |           <artifactId>maven-clean-plugin</artifactId>
43 |           <version>3.1.0</version>
44 |         </plugin>
45 |         <!-- default lifecycle, jar packaging: see https://maven.apache.org/ref/current/maven-core/default-bindings.html#Plugin_bindings_for_jar_packaging -->
46 |         <plugin>
47 |           <artifactId>maven-resources-plugin</artifactId>
48 |           <version>3.0.2</version>
49 |         </plugin>
50 |         <plugin>
51 |           <artifactId>maven-compiler-plugin</artifactId>
52 |           <version>3.8.0</version>
53 |         </plugin>
54 |         <plugin>
55 |           <artifactId>maven-surefire-plugin</artifactId>
56 |           <version>2.22.1</version>
57 |         </plugin>
58 |         <plugin>
59 |           <artifactId>maven-jar-plugin</artifactId>
60 |           <version>3.0.2</version>
61 |         </plugin>
62 |         <plugin>
63 |           <artifactId>maven-install-plugin</artifactId>
64 |           <version>2.5.2</version>
65 |         </plugin>
66 |         <plugin>
67 |           <artifactId>maven-deploy-plugin</artifactId>
68 |           <version>2.8.2</version>
69 |         </plugin>
70 |         <!-- site lifecycle, see https://maven.apache.org/ref/current/maven-core/lifecycles.html#site_Lifecycle -->
71 |         <plugin>
72 |           <artifactId>maven-site-plugin</artifactId>
73 |           <version>3.7.1</version>
74 |         </plugin>
75 |         <plugin>
76 |           <artifactId>maven-project-info-reports-plugin</artifactId>
77 |           <version>3.0.0</version>
78 |         </plugin>
79 |       </plugins>
80 |     </pluginManagement>
81 |   </build>
82 | </project>
83 | 


--------------------------------------------------------------------------------
/src/main/java/bistu/server/Serve.java:
--------------------------------------------------------------------------------
  1 | package bistu.server;
  2 | 
  3 | import java.io.ObjectInputStream;
  4 | import java.io.ObjectOutputStream;
  5 | import java.io.IOException;
  6 | import java.net.Socket;
  7 | import java.util.logging.Logger;
  8 | import java.util.logging.Level;
  9 | import java.util.List;
 10 | 
 11 | import bistu.share.Detail;
 12 | import bistu.share.Overview;
 13 | import bistu.share.Instruction;
 14 | import bistu.db.DbUtil;
 15 | 
 16 | public class Serve implements Runnable {
 17 | 
 18 |     private Socket socket;
 19 |     private DbUtil db;
 20 |     private String logName;
 21 |     private Logger logger;
 22 | 
 23 |     private ObjectInputStream objectIn;
 24 |     private ObjectOutputStream objectOut;
 25 | 
 26 |     private boolean fine = true;
 27 | 
 28 |     Serve(Socket socket) {
 29 |         this.socket = socket;
 30 |         int port = socket.getPort();
 31 |         String addr = socket.getInetAddress().getHostAddress();
 32 |         this.logName = String.format("Serve for %s:%d", addr, port);
 33 |         this.logger = Logger.getLogger(this.logName);
 34 |         this.db = DbUtil.getInstance();
 35 |     }
 36 | 
 37 |     private void serve_SERVE_END() throws IOException {
 38 |         socket.close();
 39 |         this.fine = false;
 40 |         logger.log(Level.INFO, "received SERVE_END sign, finish service.");
 41 |     }
 42 | 
 43 |     private void serve_GET_LIST() throws IOException {
 44 |         List<Overview> stickies = db.getList();
 45 |         if (stickies != null) {
 46 |             objectOut.writeInt(Instruction.FINE_CODE);
 47 |             objectOut.writeObject(stickies);
 48 |         } else {
 49 |             objectOut.writeInt(Instruction.ERR_CODE);
 50 |         }
 51 |         objectOut.flush();
 52 |     }
 53 | 
 54 |     private void serve_GET_DETAIL() throws IOException {
 55 |         long id = objectIn.readLong();
 56 |         Detail detail = db.getDetail(id);
 57 |         if (detail != null) {
 58 |             objectOut.writeInt(Instruction.FINE_CODE);
 59 |             objectOut.writeObject(detail);
 60 |         } else {
 61 |             objectOut.writeInt(Instruction.ERR_CODE);
 62 |         }
 63 |         objectOut.flush();
 64 |     }
 65 | 
 66 |     private void serve_ADD_STICKY() throws IOException {
 67 |         long id = db.insertSticky();
 68 |         if (id > 0) {
 69 |             objectOut.writeInt(Instruction.FINE_CODE);
 70 |             objectOut.writeLong(id);
 71 |         } else {
 72 |             objectOut.writeInt(Instruction.ERR_CODE);
 73 |         }
 74 |         objectOut.flush();
 75 |     }
 76 | 
 77 |     private void serve_UPDATE_STICKY() throws IOException {
 78 |         try {
 79 |             Detail d = (Detail)objectIn.readObject();
 80 |             if (db.updateSticky(d)) {
 81 |                 objectOut.writeInt(Instruction.FINE_CODE);
 82 |             } else {
 83 |                 objectOut.writeInt(Instruction.ERR_CODE);
 84 |             }
 85 |             objectOut.flush();
 86 |             logger.log(Level.INFO, String.format("update: %s", d.toString()));
 87 |         } catch (ClassNotFoundException e) {
 88 |             logger.log(Level.SEVERE, "the class Detail not found while reading updated sticky.", e);
 89 |         }
 90 |     }
 91 |     
 92 |     private void serve_REMOVE_STICKY() throws IOException {
 93 |         long id = objectIn.readLong();
 94 |         if (db.removeSticky(id)) {
 95 |             objectOut.writeInt(Instruction.FINE_CODE);
 96 |         } else {
 97 |             objectOut.writeInt(Instruction.ERR_CODE);
 98 |         }
 99 |         objectOut.flush();
100 |     }
101 | 
102 |     private void serve() {
103 |         while (this.fine) {
104 |             try {
105 |                 switch (objectIn.readInt()) {
106 |                     case Instruction.SERVE_END:
107 |                         this.serve_SERVE_END();
108 |                         break;
109 | 
110 |                     case Instruction.GET_LIST:
111 |                         this.serve_GET_LIST();
112 |                         break;
113 | 
114 |                     case Instruction.GET_DETAIL:
115 |                         this.serve_GET_DETAIL();
116 |                         break;
117 | 
118 |                     case Instruction.ADD_STICKY:
119 |                         this.serve_ADD_STICKY();
120 |                         break;
121 | 
122 |                     case Instruction.UPDATE_STICKY:
123 |                         this.serve_UPDATE_STICKY();
124 |                         break;
125 | 
126 |                     case Instruction.REMOVE_STICKY:
127 |                         this.serve_REMOVE_STICKY();
128 |                         break;
129 |                 }
130 |             } catch (IOException e) {
131 |                 logger.log(Level.SEVERE, "error while reading/writing socket. shutting this serve.", e);
132 |                 this.fine = false;
133 |             }
134 |         }
135 |     }
136 | 
137 |     @Override
138 |     public void run() {
139 |         logger.log(Level.INFO, "a user connected.");
140 | 
141 |         try {
142 |             this.objectIn = new ObjectInputStream(socket.getInputStream());
143 |             this.objectOut = new ObjectOutputStream(socket.getOutputStream());
144 |             logger.log(Level.INFO, "inited the object stream.");
145 |         } catch (IOException e) {
146 |             logger.log(Level.SEVERE, "error occurred while initializing object stream.", e);
147 |             this.fine = false;
148 |         }
149 | 
150 |         this.serve();
151 |     }
152 | 
153 | }


--------------------------------------------------------------------------------
/src/main/java/bistu/db/DbUtil.java:
--------------------------------------------------------------------------------
  1 | package bistu.db;
  2 | 
  3 | import java.sql.Connection;
  4 | import java.sql.DriverManager;
  5 | import java.sql.PreparedStatement;
  6 | import java.sql.ResultSet;
  7 | import java.sql.SQLException;
  8 | import java.util.ArrayList;
  9 | import java.util.List;
 10 | import java.util.logging.Logger;
 11 | import java.util.logging.Level;
 12 | 
 13 | import bistu.share.Detail;
 14 | import bistu.share.Overview;
 15 | 
 16 | public class DbUtil {
 17 | 
 18 |     private static final String URL = "jdbc:mariadb://[::]:3306/db_sticky_android";
 19 |     private static final String USER = "sticky_android";
 20 |     private static final String PASSWD = "android";
 21 |     private static final String LogName = "database util";
 22 | 
 23 |     public static final String TABLE_NAME = "sticky";
 24 |     public static final String COL_ID = "c_id";
 25 |     public static final String COL_MODIFY = "c_modify";
 26 |     public static final String COL_OVERVIEW = "c_overview";
 27 |     public static final String COL_FULL_TEXT = "c_full_text";
 28 | 
 29 |     private static DbUtil db;
 30 | 
 31 |     private Connection connection;
 32 |     private PreparedStatement s_selectList;
 33 |     private PreparedStatement s_selectSticky;
 34 |     private PreparedStatement s_updateSticky;
 35 |     private PreparedStatement s_removeSticky;
 36 |     private PreparedStatement s_insertSticky;
 37 |     private PreparedStatement s_lastInsertId;
 38 |     private Logger logger;
 39 | 
 40 |     private DbUtil() {
 41 |         try {
 42 |             this.logger = Logger.getLogger(LogName);
 43 |             this.connection = DriverManager.getConnection(URL, USER, PASSWD);
 44 |             logger.log(Level.INFO, "connected to database.");
 45 |         } catch (SQLException e) {
 46 |             logger.log(Level.SEVERE, "connect to database failed!", e);
 47 |             System.exit(-1);
 48 |         }
 49 | 
 50 |         try {
 51 |             this.s_selectList = connection.prepareStatement(String.format("select %s, %s, %s from %s;", COL_ID, COL_MODIFY, COL_OVERVIEW, TABLE_NAME));
 52 |             this.s_selectSticky = connection.prepareStatement(String.format("select * from %s where %s=?;", TABLE_NAME, COL_ID));
 53 |             this.s_updateSticky = connection.prepareStatement(String.format("update %s set %s=?, %s=? where %s=?", TABLE_NAME, COL_MODIFY, COL_FULL_TEXT, COL_ID));
 54 |             this.s_removeSticky = connection.prepareStatement(String.format("delete from %s where %s=?", TABLE_NAME, COL_ID));
 55 |             this.s_insertSticky = connection.prepareStatement(String.format("insert into %s (%s) values (now());", TABLE_NAME, COL_MODIFY));
 56 |             this.s_lastInsertId = connection.prepareStatement("select last_insert_id()");
 57 |             logger.log(Level.INFO, "prepared statement.");
 58 |         } catch (SQLException e) {
 59 |             logger.log(Level.SEVERE, "preparing statement error!", e);
 60 |             System.exit(-1);
 61 |         }
 62 |     }
 63 | 
 64 |     public static DbUtil getInstance() {
 65 |         if (db == null) {
 66 |             db = new DbUtil();
 67 |             return db;
 68 |         } else {
 69 |             return db;
 70 |         }
 71 |     }
 72 | 
 73 |     /**
 74 |      * get id, modify time, overview from table
 75 |      * @return return a List<Overview>, null if error occurred.
 76 |      */
 77 |     public List<Overview> getList() {
 78 |         ResultSet rs = null;
 79 |         try {
 80 |             rs = s_selectList.executeQuery();
 81 |             logger.log(Level.INFO, "selected full list from table.");
 82 |         } catch (SQLException e) {
 83 |             logger.log(Level.SEVERE, "error occurred while selecting sticky full list!", e);
 84 |             return null;
 85 |         }
 86 | 
 87 |         ArrayList<Overview> result = new ArrayList<>();
 88 |         try {
 89 |             while (rs.next()) {
 90 |                 Overview o = new Overview(
 91 |                     rs.getLong(COL_ID),
 92 |                     rs.getTimestamp(COL_MODIFY),
 93 |                     rs.getString(COL_OVERVIEW)
 94 |                 );
 95 |                 result.add(o);
 96 |             }
 97 |             logger.log(Level.INFO, String.format("retrieved %d stickies from table.", result.size()));
 98 |         } catch (SQLException e) {
 99 |             logger.log(Level.SEVERE, "error occurred while retrieving data from resultSet!", e);
100 |             return null;
101 |         }
102 |         return result;
103 |     }
104 | 
105 |     /**
106 |      * get detail of a sticky.
107 |      * @param id the required sticky's id
108 |      * @return Detail of sticky, null if error occurred.
109 |      */
110 |     public Detail getDetail(long id) {
111 |         ResultSet rs = null;
112 |         try {
113 |             s_selectSticky.setLong(1, id);
114 |             rs = s_selectSticky.executeQuery();
115 |             s_selectSticky.clearParameters();
116 |         } catch (SQLException e) {
117 |             logger.log(Level.SEVERE, "error occurred while querying detail.", e);
118 |             return null;
119 |         }
120 | 
121 |         Detail d = null;
122 |         try {
123 |             if (rs.next()) {
124 |                 d = new Detail(
125 |                     rs.getLong(COL_ID),
126 |                     rs.getTimestamp(COL_MODIFY),
127 |                     rs.getString(COL_FULL_TEXT)
128 |                 );
129 |                 logger.log(Level.INFO, String.format("detail got: %s.", d.toString()));
130 |             } else {
131 |                 logger.log(Level.SEVERE, String.format("did not find the sticky with id: %d", id));
132 |             }
133 |         } catch (SQLException e) {
134 |             logger.log(Level.SEVERE, "error occurred while retrieving data from resultSet.", e);
135 |             return null;
136 |         }
137 |         return d;
138 |     }
139 | 
140 |     /**
141 |      * update a sticky.
142 |      * @param sticky the new sticky, should has the same id of previous sticky.
143 |      * @return true if update succeed, false if update fail or error occurred.
144 |      */
145 |     public boolean updateSticky(Detail sticky) {
146 |         boolean result = false;
147 |         try {
148 |             s_updateSticky.setTimestamp(1, sticky.getModifyTime());
149 |             s_updateSticky.setString(2, sticky.getFullText());
150 |             s_updateSticky.setLong(3, sticky.getId());
151 |             result = s_updateSticky.executeUpdate() > 0;
152 |             s_updateSticky.clearParameters();
153 |             logger.log(Level.INFO, "sticky updated.");
154 |         } catch (SQLException e) {
155 |             logger.log(Level.SEVERE, "error occurred while updating sticky.", e);
156 |         }
157 |         return result;
158 |     }
159 | 
160 |     /**
161 |      * @param id the id of sticky to be removed
162 |      * @return true if remove succeed, false if fail or error occurred.
163 |      */
164 |     public boolean removeSticky(long id) {
165 |         boolean result = false;
166 |         try {
167 |             s_removeSticky.setLong(1, id);
168 |             result = s_removeSticky.executeUpdate() > 0;
169 |             logger.log(Level.INFO, result ? "remove sticky succeed.": "removed nothing.");
170 |         } catch (SQLException e) {
171 |             logger.log(Level.SEVERE, "error occurred while removing sticky.", e);
172 |         }
173 |         return result;
174 |     }
175 | 
176 |     /**
177 |      * will create a blank sticky in database. the modify time of sticky depends on when
178 |      * the sql be run on server.
179 |      * @return sticky's id if succeed, -1 if create fail.
180 |      */
181 |     public long insertSticky() {
182 |         long id = -1;
183 |         try {
184 |             if (s_insertSticky.executeUpdate() > 0) {
185 |                 ResultSet idInserted = s_lastInsertId.executeQuery();
186 |                 idInserted.next();
187 |                 id = idInserted.getLong(1);
188 |                 logger.log(Level.INFO, String.format("inserted id=%d.", id));
189 |             }
190 |         } catch (SQLException e) {
191 |             logger.log(Level.SEVERE, "error occurred while inserting or getting id.");
192 |         }
193 |         return id;
194 |     }
195 | 
196 | }


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