1.基础类-java.util.concurrent.ExcutorService
这个类的几个重要函数
shutdown 关闭任务池,无法传入新任务
shutdownnow 关闭所有任务,包括未执行完成的任务
submit 向任务池提交任务
2.基础接口-java.util.concurrent.Future
Future就是对于具体的Runnable或者Callable任务的执行结果进行取消、查询是否完成、获取结果。必要时可以通过get方法获取执行结果，该方法会阻塞直到任务返回结果。
FutureTask 是实现了Future接口和Runnable接口,RunnableFuture接口
public class Test {
public static void main(String[] args) {
ExecutorService executor = Executors.newCachedThreadPool();
Task task = new Task();
Future<Integer> result = executor.submit(task);
executor.shutdown();
try {
Thread.sleep(1000);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
System.out.println("主线程在执行任务");
try {
System.out.println("task运行结果"+result.get());
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
System.out.println("所有任务执行完毕");
}
}
class Task implements Callable<Integer>{
@Override
public Integer call() throws Exception {
System.out.println("子线程在进行计算");
Thread.sleep(3000);
int sum = 0;
for(int i=0;i<100;i++)
sum += i;
return sum;
}
}
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public class Test {
public static void main(String[] args) {
//第一种方式
ExecutorService executor = Executors.newCachedThreadPool();
Task task = new Task();
FutureTask<Integer> futureTask = new FutureTask<Integer>(task);
executor.submit(futureTask);
executor.shutdown();
//第二种方式，注意这种方式和第一种方式效果是类似的，只不过一个使用的是ExecutorService，一个使用的是Thread
/*Task task = new Task();
FutureTask<Integer> futureTask = new FutureTask<Integer>(task);
Thread thread = new Thread(futureTask);
thread.start();*/
try {
Thread.sleep(1000);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
System.out.println("主线程在执行任务");
try {
System.out.println("task运行结果"+futureTask.get());
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
System.out.println("所有任务执行完毕");
}
}
class Task implements Callable<Integer>{
@Override
public Integer call() throws Exception {
System.out.println("子线程在进行计算");
Thread.sleep(3000);
int sum = 0;
for(int i=0;i<100;i++)
sum += i;
return sum;
}
}
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3.StaticMethod.getResult方法的优化版本,异步方式
/**
* getResult 的优化版本 异步,非阻塞方式
* @author [email protected]
* @param url 接口地址
* @param param 接口参数
*/
public static void getResult_Asynchronous(final String url, final String param) {
ExecutorService es = Executors.newCachedThreadPool();
es.submit(new Callable<String>() {
@Override
public String call() throws Exception {
PrintWriter out = null;
BufferedReader in = null;
String result = "";
try {
URL realUrl = new URL(url);
// 打开和URL之间的连接
URLConnection conn = realUrl.openConnection();
// 设置通用的请求属性
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestProperty("user-agent",
"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)");
// 发送POST请求必须设置如下两行
conn.setDoOutput(true);
conn.setDoInput(true);
// 获取URLConnection对象对应的输出流
out = new PrintWriter(new OutputStreamWriter(conn.getOutputStream(), "utf-8"));
// 发送请求参数
out.print(param);
// flush输出流的缓冲
out.flush();
// 定义BufferedReader输入流来读取URL的响应
in = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
String line;
while ((line = in.readLine()) != null) {
result += line;
}
} catch (Exception e) {
System.out.println("发送POST请求出现异常！" + e);
System.out.println("url=" + url + "?" + param);
}
// 使用finally块来关闭输出流、输入流
finally {
try {
if (out != null) {
out.close();
}
if (in != null) {
in.close();
}
} catch (IOException ex) {
}
}
return result;
}
});
es.shutdown();
}
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测试函数
public static void main(String[] args) {
System.out.println(new Date());
StaticMethod.getResult_Asynchronous("http://cs.jiwu.com/build!home.action?bid=3343", "");
System.out.println(new Date());
System.out.println(new Date());
StaticMethod.getResult("http://cs.jiwu.com/build!home.action?bid=3343", "");
System.out.println(new Date());
}
输出结果:
Fri Apr 15 14:41:22 CST 2016
Fri Apr 15 14:41:22 CST 2016
Fri Apr 15 14:41:22 CST 2016
Fri Apr 15 14:41:32 CST 2016
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结论:采用异步方式更新一个楼盘页 几乎不需要等待,而采用同步方式却花费了10s的时间,性能有巨大差距!