springbatch---->springbatch的使用（五）

　　这里我们介绍一个从数据库读取数据并写入到文件中的案例。如果能真心爱上一个人，那么不管对方是何等恶劣，哪怕对方并不爱自己，人生也至少不会是地狱，就算多少有点黯淡。

读取数据库数据

一、定义一个读写的job

<!--读取数据库数据到文件-->

<job id="readDatabaseJob">

    <step id="readDatabaseStep">

        <tasklet transaction-manager="transactionManager">

            <chunk reader="userReader" commit-interval="100" writer="userWriter"/>

        </tasklet>

    </step>

</job>

二、定义并实现读取数据库的reader

<!--读取数据库到文件中-->

<bean id="userReader" class="org.springframework.batch.item.database.JdbcCursorItemReader">

    <property name="sql" value="select user_name, age, address, birthday from batch_user where age > ?;"/>

    <property name="rowMapper" ref="userRowMapper"/>

    <property name="dataSource" ref="dataSource"/>

    <property name="preparedStatementSetter" ref="paramStatementSetterUser"/>

</bean>

<bean id="userRowMapper" class="spring.batch.readDatabase.UserRowMapper"/>

<bean id="paramStatementSetterUser" class="org.springframework.batch.core.resource.ListPreparedStatementSetter" scope="step">

    <property name="parameters">

        <list>

            <value>#{jobParameters['age']}</value>

        </list>

    </property>

</bean>

上述的UserRowMapper类代码如下

package spring.batch.readDatabase;

import org.springframework.jdbc.core.RowMapper;

import spring.batch.readFile.People;

import java.sql.ResultSet;

import java.sql.SQLException;

/**

 * @Author: huhx

 * @Date: 2017-11-02 上午 10:16

 */

public class UserRowMapper implements RowMapper<People> {

    @Override

    public People mapRow(ResultSet rs, int rowNum) throws SQLException {

        People people = new People();

        people.setUsername(rs.getString("user_name"));

        people.setAge(rs.getInt("age"));

        people.setAddress(rs.getString("address"));

        people.setBirthday(rs.getDate("birthday"));

        return people;

    }

}

三、定义并实现写入文件的writer

<bean id="userWriter" class="spring.batch.readDatabase.UserFileWriter">

    <property name="targetDirectory" value="file"/>

    <property name="targetFile" value="user.txt"/>

</bean>

UserFileWriter的实现代码

package spring.batch.readDatabase;

import org.apache.commons.io.FileUtils;

import org.springframework.batch.item.ItemWriter;

import spring.batch.readFile.People;

import java.io.File;

import java.util.List;

/**

 * @Author: huhx

 * @Date: 2017-11-02 上午 10:19

 */

public class UserFileWriter implements ItemWriter<People> {

    private String targetDirectory;

    private String targetFile;

    public void setTargetDirectory(String targetDirectory) {

        this.targetDirectory = targetDirectory;

    }

    public void setTargetFile(String targetFile) {

        this.targetFile = targetFile;

    }

    @Override

    public void write(List<? extends People> items) throws Exception {

        File targetDirectoryAsFile = new File(targetDirectory);

        if (!targetDirectoryAsFile.exists()) {

            FileUtils.forceMkdir(targetDirectoryAsFile);

        }

        File target = new File(targetDirectory, targetFile);

        FileUtils.writeLines(target, items, true);

    }

}

四、其它的一些信息及注意的地方

• 这里我们复写了People类的toString方法

@Override

public String toString() {

    return "username=" + username + "|age=" + age + "|address=" + address + "|birthday=" + birthday;

}

• JobLaunch.java类里面，我们增加参数

JobParameters jobParameters = parametersBuilder.addString("age", "25").toJobParameters();

• 数据库表user_batch的所有数据

• 最终生成的user.txt的文件内容如下

username=孙尚香|age=|address=天津|birthday=--

username=牛魔王|age=|address=武汉|birthday=--

友情链接