Java中的Properties类-蒲公英云

Java中的Properties类

た入场券 2023-06-04 06:56 156阅读 0赞

我们可以查看Properties的源码

可以看到，它是继承HashTable的，也就是说它是线程安全的，且里面的数据以键值对存储

class Properties extends Hashtable<Object,Object>

它里面实现了一个方法load（），而load中调用了load0(),可以加载配置文件

private void load0 (LineReader lr) throws IOException {
        char[] convtBuf = new char[1024];
        int limit;
        int keyLen;
        int valueStart;
        char c;
        boolean hasSep;
        boolean precedingBackslash;
        while ((limit = lr.readLine()) >= 0) {
            c = 0;
            keyLen = 0;
            valueStart = limit;
            hasSep = false;
            //System.out.println("line=<" + new String(lineBuf, 0, limit) + ">");
            precedingBackslash = false;
            while (keyLen < limit) {
                c = lr.lineBuf[keyLen];
                //need check if escaped.
                if ((c == '=' ||  c == ':') && !precedingBackslash) {
                    valueStart = keyLen + 1;
                    hasSep = true;
                    break;
                } else if ((c == ' ' || c == '\t' ||  c == '\f') && !precedingBackslash) {
                    valueStart = keyLen + 1;
                    break;
                }
                if (c == '\\') {
                    precedingBackslash = !precedingBackslash;
                } else {
                    precedingBackslash = false;
                }
                keyLen++;
            }
            while (valueStart < limit) {
                c = lr.lineBuf[valueStart];
                if (c != ' ' && c != '\t' &&  c != '\f') {
                    if (!hasSep && (c == '=' ||  c == ':')) {
                        hasSep = true;
                    } else {
                        break;
                    }
                }
                valueStart++;
            }
            String key = loadConvert(lr.lineBuf, 0, keyLen, convtBuf);
            String value = loadConvert(lr.lineBuf, valueStart, limit - valueStart, convtBuf);
            put(key, value);
        }
    }

可以看到，load0会将配置文件以：或者=为中间点，获取key和value，存入

存入之后，我们便可以通过getproperties(“key”)来获取对应的value值

InputStream inputStream=new FileInputStream("C:/Users/86186/Desktop/config.properties");
Properties properties=new Properties();
properties.load(inputStream);
String name=properties.getProperty("name");
System.out.print(name);