统计txt文件中出现的某个字符串次数

　　

代码：

参考：https://www.cnblogs.com/mlan/p/7811382.html

public class strCounts {
    //主函数
    public static int process(File file, String key){
        FileInputStream fis = null;
        int sum = 0;
        try{
           fis = new FileInputStream(file);
           int len = 0;
           byte[] buf = new byte[1024];
           String str = null;
           while((len = fis.read(buf)) !=-1){
               str = new String(buf, 0, len,"GBK");
               int count = getKeyStringCount(str,key); 
               sum = sum + count;
           }

        }catch(FileNotFoundException e){
            e.printStackTrace();
        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
           try {
               fis.close();
           } catch (IOException e) {
               e.printStackTrace();
           }
       }

       return sum;
    }

// 统计主串str中子串key出现的次数（注意，这不同于模式匹配算法！）

public static int getKeyStringCount(String str, String key) {         
    int count = 0; 
    int index = 0;
    //indexOf(key,index):返回指定子串的第一次出现的字符串中的索引，从指定的索引开始   
    while((index = str.indexOf(key,index))!=-1){      
        index = index + key.length(); 
        count++;                
    }             
    return count; 
}

// 测试

    public static void main(String[] args) {
       File file = new File("D:/test.txt");
       String key = "aa";
       int sum = process(file, key);
       System.out.println("文件中字符串"+key+"出现的次数为："+sum+"次"); 
   }
}