WebView 渲染加速

一。基本设置

1.开启硬件加速
在 Manifest 中配置 activity 支持硬件加速 android:hardwareAccelerated=”true”

2.提高优先级
设置 webview 渲染的优先级为高级
webSettings.setRenderPriority(RENDERPRIORITY.HIGH);

3.图片延时加载
开始时阻塞图片加载，mWebSettings.setBlockNetworkImage(true);
当网页加载完成时，再取消阻塞图片加载,最好在
onPageFinished(WebView view, String url) 回调方法中设置mWebSettings.setBlockNetworkImage(false);

二。缓存方式
关于 webview 缓存的介绍参见这篇博文：http://www.jianshu.com/p/5e7075f4875f
此处仅以缓存图片说明具体实现方式

/** * 图片 缓存表 */@Table(name = "cm_img_tbl")public class CmImgTbl {//主键 非空 唯一@Column(name = "id" ,isId = true,property ="not null")private int id;//图片 文件在远程服务器上的地址@Column(name = "remote_address",property = "not null")private String remoteAddress;//图片 文件在本地存储的地址@Column(name = "local_address")private String localAddress;//数据插入时间@Column(name = "insert_time")private long insertTime;//数据更新时间@Column(name = "update_time")private long updateTime;@Column(name = "file_size",property = "not null")private long fileSize;//资源访问时间@Column(name = "visit_time")private long visitTime;public long getVisitTime() {    return visitTime;}public void setVisitTime(long visitTime) {    this.visitTime = visitTime;}public long getFileSize() {    return fileSize;}public void setFileSize(long fileSize) {    this.fileSize = fileSize;}public int getId() {    return id;}public void setId(int id) {    this.id = id;}public String getRemoteAddress() {    return remoteAddress;}public void setRemoteAddress(String remoteAddress) {    this.remoteAddress = remoteAddress;}public String getLocalAddress() {    return localAddress;}public void setLocalAddress(String localAddress) {    this.localAddress = localAddress;}public long getInsertTime() {    return insertTime;}public void setInsertTime(long insertTime) {    this.insertTime = insertTime;}public long getUpdateTime() {    return updateTime;}public void setUpdateTime(long updateTime) {    this.updateTime = updateTime;}@Overridepublic String toString() {    return "CmImgTbl{" +            "id=" + id +            ", remoteAddress='" + remoteAddress + '\'' +            ", localAddress='" + localAddress + '\'' +            ", insertTime=" + insertTime +            ", updateTime=" + updateTime +            ", fileSize=" + fileSize +            ", visitTime=" + visitTime +            '}';}}DAO部分@Route(path = "/basemodule/cache/img") public class ImgCacheServiceImpl implements IImgCacheService {private final String TAG = getClass().getSimpleName().toString();private SystemConfig config;private DbManager manager;@Overridepublic void init(Context context) {    //获取到系统配置    Object obj = SingletonManager.INSTANCE.getObj(Tag.TAG_SINGLETON_SYSTEM_CONFIG_HOLDER);    if (obj instanceof SystemConfig) {        config = (SystemConfig) obj;    }    try {        DbManager.DaoConfig daoConfig = new DbManager.DaoConfig()                //设置数据库名                .setDbName(config.getDB_NAME())                //设置数据库路径                .setDbDir(new File(config.getDB_DIR()))                //设置数据库版本                .setDbVersion(ApplicationUtil.getLocalVersion(config.getContext()))                //设置开启事务                .setAllowTransaction(true)                //监听数据库打开                .setDbOpenListener(new DbManager.DbOpenListener() {                    @Override                    public void onDbOpened(DbManager db) {                        LogUtil.e(TAG, "数据库开启");                    }                })                //监听数据库版本升级                .setDbUpgradeListener(new DbManager.DbUpgradeListener() {                    @Override                    public void onUpgrade(DbManager db, int oldVersion, int newVersion) {                        LogUtil.e(TAG, "数据库版本升级：" + oldVersion + "-->" + newVersion);                        db.getDaoConfig().setDbVersion(newVersion);                    }                })                .setTableCreateListener(new DbManager.TableCreateListener() {                    @Override                    public void onTableCreated(DbManager db, TableEntity<?> table) {                        LogUtil.e(TAG, "数据表创建：" + table.getName());                    }                });        manager = x.getDb(daoConfig);    } catch (Exception e) {        e.printStackTrace();        LogUtil.e(TAG, "DBManager 创建失败");    }}/** * 保存img 文件 * @param img */@Overridepublic void saveImgFile(CmImgTbl img) {    if (img == null) {        LogUtil.e("img==null");        return;    }    if (!manager.getDatabase().isOpen()) {        manager = x.getDb(manager.getDaoConfig());    }    try {        //检查数据库是否有该条数据，没有则直接插入新记录        if(manager.selector(CmImgTbl.class).where("remote_address","=",img.getRemoteAddress()).count()<=0){            manager.save(img);        }else {            //已经有历史纪录，更新属性            CmImgTbl tempImg=manager.selector(CmImgTbl.class).where("remote_address","=",img.getRemoteAddress()).findFirst();            tempImg.setUpdateTime(img.getUpdateTime());            tempImg.setLocalAddress(img.getLocalAddress());            tempImg.setFileSize(img.getFileSize());            manager.update(tempImg,"update_time");            manager.update(tempImg,"local_address");            manager.update(tempImg,"file_size");            manager.update(tempImg,"visit_time");        }    } catch (DbException e) {        e.printStackTrace();    }    finally { //            try { //                manager.close(); //            } catch (IOException e) { //                e.printStackTrace(); //            }    }}/** * 通过远程连接获取本地img文件地址 * @param remoteAddress * @return */@Overridepublic  String getLocalImgAddress(String remoteAddress){    if(remoteAddress==null || remoteAddress.isEmpty()){        return "N";    }    if(!manager.getDatabase().isOpen()){        manager=x.getDb(manager.getDaoConfig());    }    try {        CmImgTbl tempImg=manager.selector(CmImgTbl.class).where("remote_address","=",remoteAddress).findFirst();        if(tempImg==null || tempImg.getLocalAddress()==null){            return "N";        }else {            String local=tempImg.getLocalAddress();            tempImg.setVisitTime(TimeUtil.getTimestamp());            //更新访问时间            manager.update(tempImg,"visit_time");            return local;        }    } catch (DbException e) {        e.printStackTrace();    }    finally {

// try {
// manager.close();
// } catch (IOException e) {
// e.printStackTrace();
// }
}

    return "N";}@Overridepublic CmImgTbl getCmImgTblByUrl(String url) {    if(url==null || url.isEmpty()){        return null;    }    if(!manager.getDatabase().isOpen()){        manager=x.getDb(manager.getDaoConfig());    }    try {        CmImgTbl tempImg=manager.selector(CmImgTbl.class).where("remote_address","=",url).findFirst();        return tempImg;    } catch (DbException e) {        e.printStackTrace();    }finally {//            try {//                manager.close();//            } catch (IOException e) {//                e.printStackTrace();//            }    }    return null;}/** * 自动清理图片 */@Overridepublic void autoClearImgCache() {    if(!manager.getDatabase().isOpen()){        manager=x.getDb(manager.getDaoConfig());    }    CacheUtil.deleteTemp(new File(com.sctjsj.basemodule.cache.commen.config.WEB_CACHE_DIR));    Calendar calendar=Calendar.getInstance();    //自动清理一个月没有访问的数据    calendar.add(Calendar.MONTH, -1);    long start=calendar.getTime().getTime();    try {        List<CmImgTbl> list=manager.selector(CmImgTbl.class).where("visit_time","<",start).findAll();        if(list==null){            return;        }        for (CmImgTbl c:list){            //删除文件            File file=new File(c.getLocalAddress());            if(file.exists() && file.isFile()){                file.delete();            }            //清空数据库            manager.deleteById(CmImgTbl.class,c.getId());        }    } catch (DbException e) {        e.printStackTrace();    }}@Overridepublic void clearAllCache() {    if(!manager.getDatabase().isOpen()){        manager=x.getDb(manager.getDaoConfig());    }    try {        List<CmImgTbl> list=manager.selector(CmImgTbl.class).findAll();        if(list==null){            return;        }        for (CmImgTbl c:list){            //删除文件            File file=new File(c.getLocalAddress());            if(file.exists() && file.isFile()){                boolean res=file.delete();            }            //清空数据库            manager.deleteById(CmImgTbl.class,c.getId());        }    } catch (DbException e) {        e.printStackTrace();    }}}

拦截资源请求，替换网络资源为本地资源

@Overridepublic WebResourceResponse shouldInterceptRequest(WebView webView, String s) {                //缓存图片            if (s.endsWith(".jpg") || s.endsWith(".JPG") || s.endsWith(".png") || s.endsWith("PNG")) {                String local = imgCacheService.getLocalImgAddress(s);                //本地没有，直接下载                if ("N".equals(local)) {                    httpService.loadWebResource(s, "img");                    return super.shouldInterceptRequest(webView, s);                } else {                    InputStream isImg = null;                    try {                        isImg = new FileInputStream(local);                    } catch (FileNotFoundException e) {                        e.printStackTrace();                        return super.shouldInterceptRequest(webView,s);                    }                    WebResourceResponse response = new WebResourceResponse("image/jpg", "UTF-8", isImg);                    return response;                }            }            if (s.endsWith(".js")) {                String local = jsCacheService.getLocalJsAddress(s);                //本地没有，直接下载                if ("N".equals(local)) {                    httpService.loadWebResource(s, "js");                    return super.shouldInterceptRequest(webView, s);                } else {                    InputStream is = null;                    try {                        is = new FileInputStream(local);                        WebResourceResponse response = new WebResourceResponse("text/html", "utf-8", is);                        return response;                    } catch (IOException e) {                        e.printStackTrace();                        return super.shouldInterceptRequest(webView,s);                    }                }            }            //缓存 css            if (s.endsWith(".css")) {                String local = cssCacheService.getLocalCssAddress(s);                //本地没有，直接下载                if ("N".equals(local)) {                    httpService.loadWebResource(s, "css");                    return super.shouldInterceptRequest(webView, s);                } else {                    InputStream is = null;                    try {                        is = new FileInputStream(local);                        WebResourceResponse response = new WebResourceResponse("text/html", "utf-8", is);                        return response;                    } catch (IOException e) {                        e.printStackTrace();                        return super.shouldInterceptRequest(webView,s);                    }                }            }            return super.shouldInterceptRequest(webView, s);        }

四。注意事项

1.注意频繁的开启和关闭数据库，读写文件，需要做好各种异常处理2.在下载资源文件时，可能还未下载完成，用户就已经结束该页面了，对于这种情况，下载的临时文件一定要定期清除3.对于一个月之内没有访问过的资源文件要予以自动清除