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=--