0065 Berkeley DB的基本用法【基础】

最新推荐文章于 2017-10-27 13:08:06 发布
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#Java #BDB #sleepycat #基本用法
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本文介绍了一个基于Sleepycat的BDB数据库操作类，包括数据库的开启与关闭方法、数据存储、数据查询及删除等功能，并提供了详细的实现代码。
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001
package demos.bdb;

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import java.io.File;

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import com.sleepycat.je.Cursor;

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import com.sleepycat.je.Database;

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import com.sleepycat.je.DatabaseConfig;

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import com.sleepycat.je.DatabaseEntry;

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import com.sleepycat.je.Environment;

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import com.sleepycat.je.EnvironmentConfig;

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import com.sleepycat.je.LockMode;

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import com.sleepycat.je.OperationStatus;

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import com.sleepycat.je.Transaction;

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import com.sleepycat.je.TransactionConfig;

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/*

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 *
 数据库操作类

017
 */

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public
 class BDB {

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020
    private
 static Database bdb; // 数据源

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    private
 static Environment exampleEnv;// 环境对象

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    private
 static boolean isrunning = false;// 判断是否运行

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    /**

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     *
 打开数据库方法

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     */

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    public
 static void start(String path) {

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        if
 (isrunning) {

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            return;

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        }

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        /********************
 文件处理 ***********************/

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        File
 envDir = new File(path);// 操作文件

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        if
 (!envDir.exists())// 判断文件路径是否存在，不存在则创建

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        {

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            envDir.mkdir();//
 创建

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        }

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        /********************
 环境配置 ***********************/

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        EnvironmentConfig
 envConfig = new EnvironmentConfig();

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        envConfig.setTransactional(false);
 // 不进行事务处理

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        envConfig.setAllowCreate(true);
 // 如果不存在则创建一个

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        exampleEnv
 = new Environment(envDir, envConfig);// 通过路径，设置属性进行创建

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        /*******************
 创建适配器对象 ******************/

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        DatabaseConfig
 dbConfig = new DatabaseConfig();

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        dbConfig.setTransactional(false);
 // 不进行事务处理

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        dbConfig.setAllowCreate(true);//
 如果不存在则创建一个

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        dbConfig.setSortedDuplicates(true);//
 数据分类

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        bdb
 = exampleEnv.openDatabase(null, "simpleDb", dbConfig); // 使用适配器打开数据库

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        isrunning
 = true; // 设定是否运行

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    }

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    /**

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     *
 关闭数据库方法

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     */

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    public
 static void stop() {

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        if
 (isrunning) {

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            isrunning
 = false;

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            bdb.close();

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            exampleEnv.close();

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        }

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    }

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    public
 static boolean isrunning() {

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        return
 isrunning;

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    }

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    /**

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     *
 数据存储方法 set(Here describes this method function with a few words)

071
     *

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     *
 TODO(Here describes this method to be suitable the condition - to be

073
     *
 possible to elect)

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     *

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     *
 @param key

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     *
 @param data

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     *

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     *           
 void

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     */

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    public
 static void set(byte[] key, byte[] data) {

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        DatabaseEntry
 keyEntry = new DatabaseEntry();

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        DatabaseEntry
 dataEntry = new DatabaseEntry();

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        keyEntry.setData(key);
 // 存储数据

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        dataEntry.setData(data);

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        OperationStatus
 status = bdb.put(null, keyEntry, dataEntry);// 持久化数据

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        if
 (status != OperationStatus.SUCCESS) {

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            throw
 new RuntimeException("Data insertion got status " + status);

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        }

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    }

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    /*

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     *
 执行获取,根据key值获取

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     */

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    public
 static void selectByKey(String aKey) {

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        DatabaseEntry
 theKey =null;

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        DatabaseEntry
 theData = new DatabaseEntry();

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        try
 {

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             theKey
 = new DatabaseEntry(aKey.getBytes("utf-8"));

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        }
 catch (Exception e) {

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            //
 TODO Auto-generated catch block

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            e.printStackTrace();

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        }

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        if
 (bdb.get(null,theKey, theData,

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                LockMode.DEFAULT)
 == OperationStatus.SUCCESS) { //根据key值，进行数据查询

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            //
 Recreate the data String.

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            byte[]
 retData = theData.getData();

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            String
 foundData = new String(retData);

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            System.out.println("For
 key: '" + aKey + "' found data: '"

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                    +
 foundData + "'.");

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        }

115
         
116
    }

117
     
118
     
119
    /**

120
     *
 查询所有，可遍历数据

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     *
 selectAll(Here describes this method function with a few words)  

122
     *

123
     *
 TODO(Here describes this method to be suitable the condition - to be possible to elect)

124
     * 

125
     *

126
     *
 void

127
     */

128
    public
 static void selectAll() {

129
        Cursor
 cursor = null;

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        cursor=bdb.openCursor(null,
 null);

131
        DatabaseEntry
 theKey=null;

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        DatabaseEntry
 theData=null;    

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        theKey
 = new DatabaseEntry();

134
        theData
 = new DatabaseEntry();

135
         
136
        while
 (cursor.getNext(theKey, theData, LockMode.DEFAULT) == OperationStatus.SUCCESS) {

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            System.out.println(new
 String(theData.getData()));

138
        }

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        cursor.close();

140
         
141
    }

142
     
143
     
144
    /**

145
     * 
 删除方法

146
     *
 delete(Here describes this method function with a few words)  

147
     *

148
     *
 TODO(Here describes this method to be suitable the condition - to be possible to elect)

149
     *

150
     *
 @param key

151
     *

152
     *
 void

153
     */

154
    public static void delete(String
 key) {

155
        DatabaseEntry
 keyEntry =null;

156
        try {

157
            keyEntry
 = new DatabaseEntry(key.getBytes("utf-8"));

158
        } catch (Exception
 e) {

159
            e.printStackTrace();

160
        }

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        bdb.delete(null,
 keyEntry);

162
    }

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}