解决问题:
在我们开发过程中总会遇到比如在线程中需要代用service或者mapper等读取数据库,或者某些自动注入bean失效的情况
问题分析:
在线程中因为线程是安全的,所以是无法自动注入bean的
解决方法:
1.在构造方法中通过工具类获取需要的bean
工具类代码:
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
/**
* @author yang
* @decription 通过工具类获取需要的的bean
*/
@Component
public class BeanContextUtils implements ApplicationContextAware {
/**
* 上下文对象实例
*/
private static ApplicationContext applicationContext;
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
/**
* 获取applicationContext
*
* @return
*/
public static ApplicationContext getApplicationContext() {
return applicationContext;
}
/**
* 通过name获取 Bean.
*
* @param name
* @return
*/
public static Object getBean(String name) {
return getApplicationContext().getBean(name);
}
/**
* 通过class获取Bean.
*
* @param clazz
* @param <T>
* @return
*/
public static <T> T getBean(Class<T> clazz) {
return getApplicationContext().getBean(clazz);
}
/**
* 通过name,以及Clazz返回指定的Bean
*
* @param name
* @param clazz
* @param <T>
* @return
*/
public static <T> T getBean(String name, Class<T> clazz) {
return getApplicationContext().getBean(name, clazz);
}
}
测试线程代码:
public class TestThread implements Runnable {
private ISysUserService iSysUserService;
public TestThread(){
this.iSysUserService = BeanContextUtils.getBean(ISysUserService.class);
}
@Override
public void run() {
SysUser sysUser = iSysUserService.selectUserById(1l);
System.out.println("测试通过工具类获取bean 获取用户名 : {} "+sysUser.getUserName());
}
}
调用线程执行:
TestThread testThread = new TestThread();
testThread.run();
测试结果:
注意:类上面不需要添加@Component,@Service等注解
2.通过set方法注入bean
测试线程代码:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
@Component
public class TestThread implements Runnable {
private static ISysUserService iSysUserService;
@Autowired
public void setISysUserService(ISysUserService iSysUserService){
TestThread.iSysUserService = iSysUserService;
}
@Override
public void run() {
SysUser sysUser = iSysUserService.selectUserById(1l);
System.out.println("测试通过set方法获取bean 获取用户名 : {} "+sysUser.getUserName());
}
}
调用代码:
TestThread testThread = new TestThread();
testThread.run();
测试结果:
注意:类上面需要添加@Component注解
3.通过静态初始化执行类的方式调用类中的bean
测试线程代码:
import javax.annotation.PostConstruct;
@Component
public class TestThread implements Runnable {
@Autowired
private ISysUserService iSysUserService;
//创建静态的线程类属性
private static TestThread testThread;
@PostConstruct
public void testThreadInit(){
System.out.println("执行成功");
testThread = this;
}
@Override
public void run() {
SysUser sysUser = this.testThread.iSysUserService.selectUserById(1l);
System.out.println("测试通过静态初始化执行类 获取bean 获取用户名 : {} "+sysUser.getUserName());
}
}
调用测试:
TestThread testThread = new TestThread();
testThread.run();
测试结果:
4.通过有参构造方法传入
测试线程代码:
public class TestThread implements Runnable {
private ISysUserService iSysUserService;
public TestThread(ISysUserService iSysUserService){
this.iSysUserService = iSysUserService;
}
@Override
public void run() {
SysUser sysUser = iSysUserService.selectUserById(1l);
System.out.println("测试通过有参构造方法传入 获取bean 获取用户名 : {} "+sysUser.getUserName());
}
}
调用代码:
//在引用类中自动注入bean或者其他方式注入bean
@Autowired
private ISysUserService iSysUserService;
//再引用方法中引用测试线程
TestThread testThread = new TestThread(iSysUserService);
testThread.run();
测试结果:
亲测可用,还有以上的bean是自己创建,这里就不出示实例啦!!!
这里也有其他的bean注入方式仅供参考
注入bean的其他几种方式