增加timestamp，缓存机制，和404处理

app/src/main/java/com/gh/common/util/FileUtils.java

@@ -7,6 +7,8 @@ import android.os.StrictMode;
 
 import org.json.JSONObject;
 
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
 import java.io.DataInputStream;
 import java.io.DataOutputStream;
 import java.io.File;
@@ -291,4 +293,78 @@ public class FileUtils {
 		return null;
 	}
 
+	// 读取文件，返回byte[]
+	public static byte[] readFile(File file) {
+		if (file == null) {
+			return null;
+		}
+		FileInputStream fis = null;
+		ByteArrayOutputStream bos = null;
+		try {
+			fis = new FileInputStream(file);
+			bos = new ByteArrayOutputStream();
+			byte[] buffer = new byte[2048];
+			int len;
+			while ((len = fis.read(buffer)) != -1) {
+				bos.write(buffer, 0, len);
+			}
+			bos.flush();
+			return bos.toByteArray();
+		} catch (IOException e) {
+			e.printStackTrace();
+		} finally {
+			if (fis != null) {
+				try {
+					fis.close();
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
+			}
+			if (bos != null) {
+				try {
+					bos.close();
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
+			}
+		}
+		return null;
+	}
+
+	// 根据byte[]，保存文件
+	public static void saveFile(File file, byte[] data) {
+		if (file == null || data == null) {
+			return;
+		}
+		ByteArrayInputStream bis = null;
+		FileOutputStream fos = null;
+		try {
+			bis = new ByteArrayInputStream(data);
+			fos = new FileOutputStream(file);
+			byte[] buffer = new byte[2048];
+			int len;
+			while ((len = bis.read(buffer)) != -1) {
+				fos.write(buffer, 0, len);
+			}
+			fos.flush();
+		} catch (IOException e) {
+			e.printStackTrace();
+		} finally {
+			if (bis != null) {
+				try {
+					bis.close();
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
+			}
+			if (fos != null) {
+				try {
+					fos.close();
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
+			}
+		}
+	}
+
 }