一、简单版
1 import java.io.FileInputStream;
2 void readFileOnLine(){
3 String strFileName = "Filename.txt";
4 FileInputStream fis = openFileInput(strFileName);
5 StringBuffer sBuffer = new StringBuffer();
6 DataInputStream dataIO = new DataInputStream(fis);
7 String strLine = null;
8 while((strLine = dataIO.readLine()) != null) {
9 sBuffer.append(strLine + “\n");
10 }
11 dataIO.close();
12 fis.close();
13 }
二、简洁版
public static String ReadTxtFile(String strFilePath)
{
String path = strFilePath;
String content = ""; //文件内容字符串
File file = new File(path); //打开文件
if (file.isDirectory()) //如果path是传递过来的参数，可以做一个非目录的判断
{
Log.d("TestFile", "The File doesn‘t not exist.");
}
else
{
try {
InputStream instream = new FileInputStream(file);
if (instream != null)
{
InputStreamReader inputreader = new InputStreamReader(instream);
BufferedReader buffreader = new BufferedReader(inputreader);
String line;
//分行读取
while (( line = buffreader.readLine()) != null) {
content += line + "\n";
}
instream.close();
}
}
catch (java.io.FileNotFoundException e)
{
Log.d("TestFile", "The File doesn‘t not exist.");
}
catch (IOException e)
{
Log.d("TestFile", e.getMessage());
}
}
return content;
}
三、用于长时间使用的apk，并且有规律性的数据
1，逐行读取文件内容
1 //首先定义一个数据类型，用于保存读取文件的内容
2 class WeightRecord {
3 String timestamp;
4 float weight;
5 public WeightRecord(String timestamp, float weight) {
6 this.timestamp = timestamp;
7 this.weight = weight;
8
9 }
10 }
11
12 //开始读取
13 private WeightRecord[] readLog() throws Exception {
14 ArrayList<WeightRecord> result = new ArrayList<WeightRecord>();
15 File root = Environment.getExternalStorageDirectory();
16 if (root == null)
17 throw new Exception("external storage dir not found");
18 //首先找到文件
19 File weightLogFile = new File(root,WeightService.LOGFILEPATH);
20 if (!weightLogFile.exists())
21 throw new Exception("logfile ‘"+weightLogFile+"‘ not found");
22 if (!weightLogFile.canRead())
23 throw new Exception("logfile ‘"+weightLogFile+"‘ not readable");
24 long modtime = weightLogFile.lastModified();
25 if (modtime == lastRecordFileModtime)
26 return lastLog;
27 // file exists, is readable, and is recently modified -- reread it.
28 lastRecordFileModtime = modtime;
29 // 然后将文件转化成字节流读取
30 FileReader reader = new FileReader(weightLogFile);
31 BufferedReader in = new BufferedReader(reader);
32 long currentTime = -1;
33 //逐行读取
34 String line = in.readLine();
35 while (line != null) {
36 WeightRecord rec = parseLine(line);
37 if (rec == null)
38 Log.e(TAG, "could not parse line: ‘"+line+"‘");
39 else if (Long.parseLong(rec.timestamp) < currentTime)
40 Log.e(TAG, "ignoring ‘"+line+"‘ since it‘s older than prev log line");
41 else {
42 Log.i(TAG,"line="+rec);
43 result.add(rec);
44 currentTime = Long.parseLong(rec.timestamp);
45 }
46 line = in.readLine();
47 }
48 in.close();
49 lastLog = (WeightRecord[]) result.toArray(new WeightRecord[result.size()]);
50 return lastLog;
51 }
52 //解析每一行
53 private WeightRecord parseLine(String line) {
54 if (line == null)
55 return null;
56 String[] split = line.split("[;]");
57 if (split.length < 2)
58 return null;
59 if (split[0].equals("Date"))
60 return null;
61 try {
62 String timestamp =(split[0]);
63 float weight = Float.parseFloat(split[1]) ;
64 return new WeightRecord(timestamp,weight);
65 }
66 catch (Exception e) {
67 Log.e(TAG,"Invalid format in line ‘"+line+"‘");
68 return null;
69 }
70 }
2，保存为文件
1 public boolean logWeight(Intent batteryChangeIntent) {
2 Log.i(TAG, "logBattery");
3 if (batteryChangeIntent == null)
4 return false;
5 try {
6 FileWriter out = null;
7 if (mWeightLogFile != null) {
8 try {
9 out = new FileWriter(mWeightLogFile, true);
10 }
11 catch (Exception e) {}
12 }
13 if (out == null) {
14 File root = Environment.getExternalStorageDirectory();
15 if (root == null)
16 throw new Exception("external storage dir not found");
17 mWeightLogFile = new File(root,WeightService.LOGFILEPATH);
18 boolean fileExists = mWeightLogFile.exists();
19 if (!fileExists) {
20 if(!mWeightLogFile.getParentFile().mkdirs()){
21 Toast.makeText(this, "create file failed", Toast.LENGTH_SHORT).show();
22 }
23 mWeightLogFile.createNewFile();
24 }
25 if (!mWeightLogFile.exists()) {
26 Log.i(TAG, "out = null");
27 throw new Exception("creation of file ‘"+mWeightLogFile.toString()+"‘ failed");
28 }
29 if (!mWeightLogFile.canWrite())
30 throw new Exception("file ‘"+mWeightLogFile.toString()+"‘ is not writable");
31 out = new FileWriter(mWeightLogFile, true);
32 if (!fileExists) {
33 String header = createHeadLine();
34 out.write(header);
35 out.write(‘\n‘);
36 }
37 }
38 Log.i(TAG, "out != null");
39 String extras = createBatteryInfoLine(batteryChangeIntent);
40 out.write(extras);
41 out.write(‘\n‘);
42 out.flush();
43 out.close();
44 return true;
45 } catch (Exception e) {
46 Log.e(TAG,e.getMessage(),e);
47 return false;
48 }
49 }
时间： 2024-08-05 11:17:49