AndServer支持206

PartialContentInterceptor.java

package com.hoowu.smart.screen.server;

import android.support.annotation.NonNull;
import android.text.TextUtils;

import com.hoowu.smart.screen.SmartScreenApplication;
import com.hoowu.smart.screen.common.Constants;
import com.hoowu.smart.screen.core.manager.AppManager;
import com.yanzhenjie.andserver.annotation.Interceptor;
import com.yanzhenjie.andserver.framework.HandlerInterceptor;
import com.yanzhenjie.andserver.framework.handler.RequestHandler;
import com.yanzhenjie.andserver.http.HttpRequest;
import com.yanzhenjie.andserver.http.HttpResponse;
import com.yanzhenjie.andserver.util.MediaType;
import com.yanzhenjie.andserver.util.StatusCode;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

@Interceptor
public class PartialContentInterceptor implements HandlerInterceptor {
    @Override
    public boolean onIntercept(@NonNull HttpRequest request, @NonNull HttpResponse response, @NonNull RequestHandler handler) throws IOException {
        String range = request.getHeader("Range");
        if (!TextUtils.isEmpty(range)) {

            File file = new File(Constants.HOOWU_STORAGE_PATH
                    + ((SmartScreenApplication) AppManager.getAppManager().getContext()).agentConfig.getStoreBasePath()
                    + request.getURI());

            //开始下载位置
            long startByte = 0;
            //结束下载位置
            long endByte = file.length() - 1;

            //有range的话
            if (range != null && range.contains("bytes=") && range.contains("-")) {
                range = range.substring(range.lastIndexOf("=") + 1).trim();
                String ranges[] = range.split("-");
                try {
                    //判断range的类型
                    if (ranges.length == 1) {
                        //类型一：bytes=-2343
                        if (range.startsWith("-")) {
                            endByte = Long.parseLong(ranges[0]);
                        }
                        //类型二：bytes=2343-
                        else if (range.endsWith("-")) {
                            startByte = Long.parseLong(ranges[0]);
                        }
                    }
                    //类型三：bytes=22-2343
                    else if (ranges.length == 2) {
                        startByte = Long.parseLong(ranges[0]);
                        endByte = Long.parseLong(ranges[1]);
                    }

                } catch (NumberFormatException e) {
                    startByte = 0;
                    endByte = file.length() - 1;
                }
            }

            //要下载的长度（为啥要加一问小学数学老师去）
            long contentLength = endByte - startByte + 1;
            //文件名
            String fileName = file.getName();
            //文件类型
            MediaType contentType = MediaType.getFileMediaType(file.getName());


            //各种响应头设置
            //参考资料：https://www.ibm.com/developerworks/cn/java/joy-down/index.html
            //坑爹地方一：看代码
            response.setHeader("Accept-Ranges", "bytes");
            //坑爹地方二：http状态码要为206
            response.setStatus(StatusCode.SC_PARTIAL_CONTENT);

//            response.setHeader("Content-Length", String.valueOf(contentLength));
            //坑爹地方三：Content-Range，格式为
            // [要下载的开始位置]-[结束位置]/[文件总大小]
            response.setHeader("Content-Range", "bytes " + startByte + "-" + endByte + "/" + file.length());


            RandomAccessFile raf = new RandomAccessFile(file, "r");

            response.setBody(new RandomFileBody(startByte, endByte, raf, contentLength, contentType));
            return true;
        } else {
            return false;
        }
    }
}

RandomFileBody.java

package com.hoowu.smart.screen.server;

import android.support.annotation.NonNull;
import android.support.annotation.Nullable;

import com.yanzhenjie.andserver.http.ResponseBody;
import com.yanzhenjie.andserver.util.MediaType;

import java.io.IOException;
import java.io.OutputStream;
import java.io.RandomAccessFile;

public class RandomFileBody implements ResponseBody {

    private Long start;
    private Long end;
    private RandomAccessFile file;
    private long mLength;
    private MediaType mMediaType;

    public RandomFileBody(Long start, Long end, RandomAccessFile file, Long length, MediaType mediaType) {
        this.start = start;
        this.end = end;
        this.file = file;
        this.mLength = length;
        this.mMediaType = mediaType;
    }

    @Override
    public long contentLength() {
        return mLength;
    }

    @Nullable
    @Override
    public MediaType contentType() {
        return mMediaType;
    }

    @Override
    public void writeTo(@NonNull OutputStream output) {
        long transmitted = 0;
        try {
            byte[] buff = new byte[10240];
            int len = 0;
            file.seek(start);
            //坑爹地方四：判断是否到了最后不足4096（buff的length）个byte这个逻辑（(transmitted + len) <= contentLength）要放前面！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！！
            //不然会会先读取randomAccessFile，造成后面读取位置出错，找了一天才发现问题所在
            while ((transmitted + len) <= mLength && (len = file.read(buff)) != -1) {
                output.write(buff, 0, len);
                output.flush();
                transmitted += len;
            }
            //处理不足buff.length部分
            if (transmitted < mLength) {
                len = file.read(buff, 0, (int) (mLength - transmitted));
                output.write(buff, 0, len);
                output.flush();
                transmitted += len;
            }

            file.close();
        } catch (IOException e) {
            System.out.println("用户停止下载：" + start + "-" + end + "：" + transmitted);
        } finally {
            try {
                if (file != null) {
                    file.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}