发布于 2017-07-14 06:36:45 | 146 次阅读 | 评论: 0 | 来源: 网友投递

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Android移动端操作系统

Android是一种基于Linux的自由及开放源代码的操作系统,主要使用于移动设备,如智能手机和平板电脑,由Google公司和开放手机联盟领导及开发。尚未有统一中文名称,中国大陆地区较多人使用“安卓”或“安致”。


InputStream.available()得到字节数,然后一次读取完,用BufferedReader.readLine()行读取再加换行符,最后用StringBuilder.append()连接成字符串,更多祥看本文
一、如何显示assets/license.txt(中文)的内容?
(1)方法1:InputStream.available()得到字节数,然后一次读取完。

 
private String readUserAgreementFromAsset(String assetName) { 
String content =""; 
try { 
InputStream is= getAssets().open(assetName); 
if (is != null){ 
DataInputStream dIs = newDataInputStream(is); 
intlength = dIs.available(); 
byte[] buffer = new byte[length]; 
dIs.read(buffer); 
content= EncodingUtils.getString(buffer, "UTF-8"); 
is.close(); 
} 
} catch (IOException e) { 
e.printStackTrace(); 
} 
return content; 
} 


(2)方法2:用BufferedReader.readLine()行读取再加换行符,最后用StringBuilder.append()连接成字符串。
A.以下是先行读取再转码UTF8:

 
private String readUserAgreementFromAsset(String assetName) { 
StringBuilder sb = newStringBuilder(""); 
String content =""; 
try { 
InputStream is= getAssets().open(assetName); 
if (is != null){ 
BufferedReader d = newBufferedReader(new InputStreamReader(is)); 
while (d.ready()) { 
sb.append(d.readLine() +"\n"); 
} 
content =EncodingUtils.getString(sb.toString().getBytes(), "UTF-8"); 
is.close(); 
} 
} catch (IOException e) { 
e.printStackTrace(); 
} 
return content; 
} 


B.以下是InputStreamReader先指定以UTF8读取文件,再进行读取读取操作:

 
private String readUserAgreementFromAsset(String assetName) { 
StringBuilder sb = newStringBuilder(""); 
String content =""; 
try { 
InputStream is= getAssets().open(assetName); 
if (is != null){ 
BufferedReaderd = new BufferedReader(new InputStreamReader(is, "UTF-8")); 
while(d.ready()) { 
sb.append(d.readLine() +"\n"); 
} 
content= sb.toString(); 
is.close(); 
} 
} catch (IOException e) { 
e.printStackTrace(); 
} 
return content; 
} 


另外,UTF8转码也可以用new String(buffer, “utf-8”)。
(3)替代方法3:将license.txt内容作为string.xml的string,如:
<stringname="license_content">用户协议
\n \n一、服务条款的确认和接纳
\n…
</string>
需要注意的是:string里需要加\n作为换行符,原来txt里的换行符在取得string后无效。
不可取方法4:每次读取4096字节,以UTF8转码,最后连接字符串。因为汉字可能被截断,导致4096的倍数附近的中文可能出现乱码。

 
private String readUserAgreementFromAsset(String assetName) { 
StringBuilder sb = newStringBuilder(""); 
String content =""; 
try { 
InputStream is= getAssets().open(assetName); 
if (is != null){ 
DataInputStream dIs = new DataInputStream(is); 
byte[] buffer = new byte[1024*4]; 
int length = 0; 
while ((length = dIs.read(buffer)) >0) { 
content =EncodingUtils.getString(buffer, 0, length, "UTF-8"); 
sb.append(content); 
} 
is.close(); 
} 
} catch (IOException e) { 
e.printStackTrace(); 
} 
return sb.toString(); 
} 


二、Android中读写文件
(1) 从resource中的raw文件夹中获取文件并读取数据(资源文件只能读不能写,\res\raw\test.txt)

 
String res = ""; 
try{ 
InputStream in = getResources().openRawResource(R.raw.test); 
int length = in.available(); 
byte [] buffer = newbyte[length]; 
in.read(buffer); 
res = EncodingUtils.getString(buffer,"UTF-8");//选择合适的编码,如果不调整会乱码 
in.close(); 
}catch(Exception e){ 
e.printStackTrace(); 
} 


(2) 从asset中获取文件并读取数据(资源文件只能读不能写,\assets\test.txt)
与raw文件夹类似,只是:
InputStream is = getAssets().open(“test.txt”);
(3) 私有文件夹下的文件存取(/data/data/包名/files/test.txt)
使用openFileOutput写文件:

 
public void writeFileData(String fileName,String message){ 
try{ 
FileOutputStream fout =openFileOutput(fileName,MODE_PRIVATE); 
byte [] bytes =message.getBytes(); 
fout.write(bytes); 
fout.close(); 
} 
catch(Exception e){ 
e.printStackTrace(); 
} 
} 


使用openFileInput读文件:

 
public String readFileData(String fileName){ 
String str = “”; 
try{ 
FileInputStream fin =openFileInput(fileName); 
int length = in.available(); 
byte [] bytes = newbyte[length]; 
fin.read(bytes); 
str = EncodingUtils.getString(bytes,"UTF-8"); 
fin.close(); 
} 
catch(Exception e){ 
e.printStackTrace(); 
} 
return str; 
} 


(4) sdcard目录下的文件存取(/mnt/sdcard/)
使用FileOutputStream写文件:

 
public void writeFile2Sdcard(String fileName,String message){ 
try{ 
FileOutputStream fout = new FileOutputStream(fileName); 
byte [] bytes =message.getBytes(); 
fout.write(bytes); 
fout.close(); 
} 
catch(Exception e){ 
e.printStackTrace(); 
} 
} 


使用FileInputStream读文件:

 
public String readFileFromSdcard(String fileName){ 
String res=""; 
try{ 
FileInputStream fin = newFileInputStream(fileName); 
int length =fin.available(); 
byte [] buffer = newbyte[length]; 
fin.read(buffer); 
res =EncodingUtils.getString(buffer, "UTF-8"); 
fin.close(); 
} 
catch(Exception e){ 
e.printStackTrace(); 
} 
return res; 
} 


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