详解利用SpringMVC拦截器控制Controller返回值

package com.tiamaes.dep.annotation; 
 
import java.lang.annotation.Documented; 
import java.lang.annotation.ElementType; 
import java.lang.annotation.Retention; 
import java.lang.annotation.RetentionPolicy; 
import java.lang.annotation.Target; 
 
@Target({ElementType.TYPE, ElementType.METHOD}) 
@Retention(RetentionPolicy.RUNTIME) 
@Documented 
public @interface Debug { 
  boolean value() default true; 
} 

package com.tiamaes.dep.annotation; 
 
import java.lang.annotation.Documented; 
import java.lang.annotation.ElementType; 
import java.lang.annotation.Retention; 
import java.lang.annotation.RetentionPolicy; 
import java.lang.annotation.Target; 
 
@Target({ElementType.TYPE, ElementType.METHOD}) 
@Retention(RetentionPolicy.RUNTIME) 
@Documented 
public @interface StringResult { 
  String value(); 
} 

package com.tiamaes.dep.interceptor; 
 
import java.io.PrintWriter; 
 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
 
import org.springframework.web.method.HandlerMethod; 
import org.springframework.web.servlet.HandlerInterceptor; 
import org.springframework.web.servlet.ModelAndView; 
 
import com.tiamaes.dep.annotation.Debug; 
import com.tiamaes.dep.annotation.StringResult; 
 
public class DebugInterceprot implements HandlerInterceptor { 
  private boolean debug = true; 
   
  public boolean preHandle(HttpServletRequest request, 
      HttpServletResponse response, Object handler) throws Exception { 
    //首先判断是否是Debug模式(全局)，如果否则使拦截器失效 
    if(!this.debug) return true; 
     
    if(handler instanceof HandlerMethod){ 
      HandlerMethod method = (HandlerMethod)handler; 
      Debug isDebug = method.getMethodAnnotation(Debug.class); 
      StringResult stringResult = method.getMethodAnnotation(StringResult.class); 
      //如果没有@StringResult注解则跳过拦截 
      //判断方法上注解的Debug值，如果否则不拦截 
      if(stringResult==null||(isDebug !=null && isDebug.value() == false)){ 
        return true; 
      }else{ 
        //拦截方法，并将stringResult中的内容返回给前台 
        PrintWriter out = response.getWriter(); 
        out.print(stringResult.value()); 
      } 
    } 
     
    return false; 
  } 
   
  public void postHandle(HttpServletRequest request, 
      HttpServletResponse response, Object handler, 
      ModelAndView modelAndView) throws Exception { 
    // TODO Auto-generated method stub 
 
  } 
 
  public void afterCompletion(HttpServletRequest request, 
      HttpServletResponse response, Object handler, Exception ex) 
      throws Exception { 
    // TODO Auto-generated method stub 
 
  } 
 
  public boolean isDebug() { 
    return debug; 
  } 
 
  public void setDebug(boolean debug) { 
    this.debug = debug; 
  } 
   
   
 
} 

<mvc:interceptors> 
  <mvc:interceptor> 
    <mvc:mapping path="/**"/> 
    <bean class="com.tiamaes.dep.interceptor.DebugInterceprot"> 
      <property name="debug" value="true"/> 
    </bean> 
  </mvc:interceptor> 
</mvc:interceptors> 

package com.tiamaes.dep.system.controller; 
 
import org.springframework.stereotype.Controller; 
import org.springframework.web.bind.annotation.RequestMapping; 
import org.springframework.web.bind.annotation.ResponseBody; 
 
import com.tiamaes.dep.annotation.Debug; 
import com.tiamaes.dep.annotation.StringResult; 
 
@Controller 
 
@RequestMapping("/test") 
public class AspectTestController { 
 
  @RequestMapping("/1") 
  @ResponseBody 
  //@Debug(false) 
  @StringResult("Interceptor") 
  public String test1(){ 
     
    return "The controller request!"; 
  } 
}