下载jar包

android-async-http-1.4.9.jar
httpclient-4.3.6.jar

HTTP请求

String url = "";

get

 RequestParams requestParams = new RequestParams();
        requestParams.put("username", "abc");
        requestParams.put("password", "123");
        client.get(url, requestParams, jsonHttpResponseHandler );

post

 RequestParams requestParams = new RequestParams();
        requestParams.put("username", "abc");
        requestParams.put("password", "123");
        client.post(url, requestParams, jsonHttpResponseHandler);

上传文件

String path1 = "";
        String path2 = "";
        RequestParams requestParams = new RequestParams();
        File file1 = new File(path1);
        File file2 = new File(path2);
        try {
            requestParams.put("file1", file1);
            requestParams.put("file2", file2);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        file1 = null;
        file2 = null;
        client.post(url, requestParams, jsonHttpResponseHandler);

下载文件

RequestParams requestParams = new RequestParams();
        requestParams.put("version", "1.1.0");
        client.post(url, requestParams, binaryHttpResponseHandler);

BinaryHttpResponseHandler类

 BinaryHttpResponseHandler binaryHttpResponseHandler = new BinaryHttpResponseHandler() {

        @Override
        public void onStart() {

        }

        @Override
        public void onProgress(long bytesWritten, long totalSize) {

        }

        @Override
        public void onSuccess(int i, Header[] headers, byte[] bytes) {

        }

        @Override
        public void onFailure(int i, Header[] headers, byte[] bytes, Throwable throwable) {
        }
    };

JsonHttpResponseHandler类

JsonHttpResponseHandler jsonHttpResponseHandler = new JsonHttpResponseHandler() {
        @Override
        public void onStart() {
            LogUtil.e_long("onStart", "onStart");
        }

        @Override
        public void onSuccess(int statusCode, Header[] headers, JSONObject response) {
            LogUtil.e_long("onSuccess", "JSONObject: "+ response.toString());
        }

        @Override
        public void onSuccess(int statusCode, Header[] headers, JSONArray response) {
            LogUtil.e_long("onSuccess", "JSONArray: "+ response.toString());
        }

        @Override
        public void onSuccess(int statusCode, Header[] headers, String responseString) {
            LogUtil.e_long("onSuccess", "responseString: "+ response.toString());
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, Throwable throwable, JSONObject errorResponse) {
            LogUtil.e_long("onFailure", "Throwable: " + throwable.getMessage() + "\nJSONObject: " + errorResponse.toString());
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, Throwable throwable, JSONArray errorResponse) {
            LogUtil.e_long("onFailure", "Throwable: " + throwable.getMessage() + "\nJSONArray: " + errorResponse.toString());
        }

        @Override
        public void onFailure(int statusCode, Header[] headers, String responseString, Throwable throwable) {
            LogUtil.e_long("onFailure", "Throwable: " + throwable.getMessage() + "\nresponseString: " + responseString);
        }

        @Override
        public void onFinish() {
            LogUtil.e_long("onFinish", "onFinish");
        }
    };

当有返回数据但是不是json格式时，会调用

  @Override
        public void onFailure(int statusCode, Header[] headers, String responseString, Throwable throwable) {
            LogUtil.e_long("onFailure", "responseString");
        }

方法。
由于该回调太过复杂，我用不成熟的手法简单封装了一下（json解析库为fastjson）：

public abstract class MyJsonResponseHandler extends JsonHttpResponseHandler {

    private Class<?> t;

    public MyJsonResponseHandler(Class<?> t) {
        this.t = t;
    }

    @Override
    public void onStart() {
        LogUtil.e_long("onStart", "onStart");
    }

    @Override
    public final void onSuccess(int statusCode, Header[] headers, JSONObject response) {
        LogUtil.e_long("onSuccess", "JSONObject: "+ response.toString());
        dealResponse(response.toString());
    }

    @Override
    public final void onSuccess(int statusCode, Header[] headers, JSONArray response) {
        LogUtil.e_long("onSuccess", "JSONArray: "+ response.toString());
        dealResponse(response.toString());
    }

    @Override
    public final void onSuccess(int statusCode, Header[] headers, String responseString) {
        LogUtil.e_long("onSuccess", "responseString: "+ responseString);
        dealResponse(responseString);
    }

    @Override
    public final void onFailure(int statusCode, Header[] headers, Throwable throwable, JSONObject errorResponse) {
        LogUtil.e_long("onFailure", "Throwable: " + throwable.getMessage() + "\nJSONObject: " + errorResponse.toString());
        onFailure(throwable);
    }

    @Override
    public final void onFailure(int statusCode, Header[] headers, Throwable throwable, JSONArray errorResponse) {
        LogUtil.e_long("onFailure", "Throwable: " + throwable.getMessage() + "\nJSONArray: " + errorResponse.toString());
        onFailure(throwable);
    }

    @Override
    public final void onFailure(int statusCode, Header[] headers, String responseString, Throwable throwable) {
        LogUtil.e_long("onFailure", "Throwable: " + throwable.getMessage() + "\nresponseString: " + responseString);
        onFailure(throwable);
    }

    @Override
    public void onFinish() {
        LogUtil.e_long("onFinish", "onFinish");
    }

    private void dealResponse(String response) {
        try {
            Object o = JSON.parseObject(response, t);
            onSuccess(o);
        } catch (Exception ex) {
            onFailure(ex);
        }
    }

    public abstract void onSuccess(Object object);

    public abstract void onFailure(Throwable throwable);

}

使用时可以这样写：

 client.get(url, requestParams, new MyJsonResponseHandler(UserInfoResponseBean.class) {

            @Override
            public void onSuccess(Object object) {
                UserInfoResponseBean responseBean = (UserInfoResponseBean) object;
                if (responseBean == null) {
                    Toast.makeText(MainActivity.this, "获取数据失败", Toast.LENGTH_SHORT).show();
                    return;
                }
                if ("1".equals(responseBean.getStat())) {
                    UserInfoBean userInfoBean = responseBean.getData();
                    // TODO: do something else...

                } else {
                    if (TextUtils.isEmpty(responseBean.getMsg())) {
                        Toast.makeText(MainActivity.this, "获取数据失败", Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(MainActivity.this, responseBean.getMsg(), Toast.LENGTH_SHORT).show();
                    }

                }
            }

            @Override
            public void onFailure(Throwable throwable) {

            }
        });

bean类为：

public class UserInfoResponseBean {
    private int stat;
    private String msg;
    private UserInfoBean data;

    //setter and getter...
}

通常情况下，返回的json格式包含stat（也有叫code），msg和data三个字段，并和服务器约定stat==1时为正确返回，0为请求结果失败。
所以为了节省代码（省去了UserInfoResponseBean）可以这样写

   private void dealResponse(String response) {
        try {
            com.alibaba.fastjson.JSONObject jsonObject = JSON.parseObject(response);
            if (jsonObject.containsKey("stat") && jsonObject.containsKey("msg") && jsonObject.containsKey("data")) {
                String stat = jsonObject.getString("stat");
                String msg = jsonObject.getString("msg");
                String data = jsonObject.getString("data");
                Object o = JSON.parseObject(data, t);
                onSuccess("1".equals(stat), msg, o);
            } else {
                onFailure(new Exception("json does not contain keys called stat msg or data"));
            }
        } catch (Exception ex) {
            onFailure(ex);
        }
    }

使用时：

client.get(url, requestParams, new MyJsonResponseHandler(UserInfoBean.class) {

            @Override
            public void onSuccess(boolean isSuccess, String msg, Object object) {
                if (isSuccess) {
                    UserInfoBean userInfoBean = (UserInfoBean) object;
                    // TODO: do something else ...

                } else {
                    if (TextUtils.isEmpty(msg)) {
                        Toast.makeText(MainActivity.this, "获取数据失败", Toast.LENGTH_SHORT).show();
                    } else {
                        Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
                    }
                }
            }

            @Override
            public void onFailure(Throwable throwable) {

            }
        });
    }

注意

AsyncHttp和xutils回调顺序不一样。
AsyncHttp：

onStart()
onFinish()
onSuccess()/onFailure()

xutils：

onStart()  
onSuccess()/onFailure()
onFinish()