在Java中如何编写回调函数，以及回调函数的简单应用

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import static java.lang.System.out;
import static java.lang.System.err;
import java.util.logging.Level;
import java.util.logging.Logger;public class CallbackExample1 {
private interface Responser {
void onSuccess(String data);
void onFailed(String prompt);
}
private static String doSomething() {
try {
out.println("开始操作...");
Thread.sleep(5000); //模拟耗时操作（如网络请求），操作正常返回"Success"，"Success"表示有效的数据
return "Success";
} catch (InterruptedException ex) {
Logger.getLogger(CallbackExample1.class.getName()).log(Level.SEVERE, null, ex);
//操作出现问题返回"Failed"，"Failed"包含错误提示，如错误码等
return "Failed";
}
}
//使用回调函数完成操作
private static void callbackDoSomething(Responser responser) {
try {
out.println("开始操作...");
Thread.sleep(5000);
responser.onSuccess("Success");
} catch (InterruptedException ex) {
Logger.getLogger(CallbackExample1.class.getName()).log(Level.SEVERE, null, ex);
responser.onFailed("Failed");
}
}
public static void main(String[] args) {
out.println("正常模式 ------ " + doSomething());
callbackDoSomething(new Responser() {
@Override
public void onSuccess(String data) {
out.println("回调模式 ------ " + data);
} @Override
public void onFailed(String prompt) {
err.println("错误提示：" + prompt);
} });
}
}

import static java.lang.System.out;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import static java.lang.System.err;
import java.net.URL;
import java.net.URLConnection;
import java.util.logging.Level;
import java.util.logging.Logger;public class CallbackExample2 {
private interface HttpResponser {
void onSuccess(String response);
void onError(String msg);
}
private static String httpRequest() {
try {
String urlStr = "http://api.eyekey.com/face/Check/checking?app_id=f89ae61fd63d4a63842277e9144a6bd2&app_key=af1cd33549c54b27ae24aeb041865da2&url=http://f.hiphotos.baidu.com/baike/pic/item/562c11dfa9ec8a1366377e5efe03918fa0ecc05a.jpg";
URLConnection c = new URL(urlStr).openConnection();
BufferedReader inputFromServer = new BufferedReader(new InputStreamReader(c.getInputStream()));
String line;
StringBuilder strBuf = new StringBuilder();
while ((line = inputFromServer.readLine()) != null) {
strBuf.append(line);
}
return strBuf.toString();
} catch (IOException ex) {
Logger.getLogger(CallbackExample2.class.getName()).log(Level.SEVERE, null, ex);
return ex.toString();
}
}
private static void callbackHttpRequest(HttpResponser httpResponser) {
try {
String urlStr = "http://api.eyekey.com/face/Check/checking?app_id=f89ae61fd63d4a63842277e9144a6bd2&app_key=af1cd33549c54b27ae24aeb041865da2&url=http://f.hiphotos.baidu.com/baike/pic/item/562c11dfa9ec8a1366377e5efe03918fa0ecc05a.jpg";
URLConnection c = new URL(urlStr).openConnection();
BufferedReader inputFromServer = new BufferedReader(new InputStreamReader(c.getInputStream()));
String line;
StringBuilder strBuf = new StringBuilder();
while ((line = inputFromServer.readLine()) != null) {
strBuf.append(line);
}
httpResponser.onSuccess(strBuf.toString());
} catch (IOException ex) {
Logger.getLogger(CallbackExample2.class.getName()).log(Level.SEVERE, null, ex);
httpResponser.onError(ex.toString());
}
}
public static void main(String[] args) {
out.println(httpRequest());
callbackHttpRequest(new HttpResponser() {
@Override
public void onSuccess(String response) {
err.println(response);
} @Override
public void onError(String msg) {
err.println(msg);
} });
}
}