写文件——FileOutputStream openFileOutput
读文件——FileInputStream openFileInput
openFileOutput写文件时当文件不存在，Android自动创建。

通过BufferedWriter直接写入字符串

public void writeFile(String inputText) {FileOutputStream outputStream = null;BufferedWriter writer = null;try {outputStream = openFileOutput("location", Context.MODE_APPEND);writer = new BufferedWriter(new OutputStreamWriter(outputStream));writer.write(inputText);} catch (IOException e) {e.printStackTrace();}finally {try {if(writer != null) {writer.close();}} catch (IOException e) {e.printStackTrace();}}
}

通过FileOutputStream也可直接写入内容此时要转成buty[]
MODE_APPEND：每次追加内容
MODE_PRIVATE：每次覆盖内容

outputStream = openFileOutput("location", Context.MODE_APPEND);
outputStream.write(inputText.getBytes());

通过BufferedReader读取文件内容

public String readFile() {FileInputStream inputStream = null;BufferedReader reader = null;StringBuilder content = new StringBuilder();try {inputStream = openFileInput("location");reader = new BufferedReader(new InputStreamReader(inputStream));String text = "";while ((text = reader.readLine()) != null) {content.append(text);}} catch (IOException e) {e.printStackTrace();} finally {if(reader != null) {try {reader.close();} catch (IOException e) {e.printStackTrace();}}}return content.toString();
}