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