public class StringUtils {
private static final char DELIM_START = '{';
private static final String DELIM_STR = "{}";
private static final char ESCAPE_CHAR = '\\';
/**
* 基于slf4j中打印日志的方法，实现字符串中{}快速替换需要的内容
* */
public static String format(final String messagePattern, final Object... argArray) {
int i = 0;
int j;
// use string builder for better multicore performance
StringBuilder sbuf = new StringBuilder(messagePattern.length() + 50);
int L;
for (L = 0; L < argArray.length; L++) {
j = messagePattern.indexOf(DELIM_STR, i);
if (j == -1) {
// no more variables
if (i == 0) { // this is a simple string
return messagePattern;
} else { // add the tail string which contains no variables and return
// the result.
sbuf.append(messagePattern, i, messagePattern.length());
return sbuf.toString();
}
} else {
if (isEscapedDelimeter(messagePattern, j)) {
if (!isDoubleEscaped(messagePattern, j)) {
L--; // DELIM_START was escaped, thus should not be incremented
sbuf.append(messagePattern, i, j - 1);
sbuf.append(DELIM_START);
i = j + 1;
} else {
// The escape character preceding the delimiter start is
// itself escaped: "abc x:\\{}"
// we have to consume one backward slash
sbuf.append(messagePattern, i, j - 1);
deeplyAppendParameter(sbuf, argArray[L], new HashMap<>());
i = j + 2;
}
} else {
// normal case
sbuf.append(messagePattern, i, j);
deeplyAppendParameter(sbuf, argArray[L], new HashMap<>());
i = j + 2;
}
}
}
// append the characters following the last {} pair.
sbuf.append(messagePattern, i, messagePattern.length());
return sbuf.toString();
}
private static boolean isDoubleEscaped(String messagePattern, int delimeterStartIndex) {
return delimeterStartIndex >= 2 && messagePattern.charAt(delimeterStartIndex - 2) == ESCAPE_CHAR;
}
private static boolean isEscapedDelimeter(String messagePattern, int delimeterStartIndex) {
if (delimeterStartIndex == 0) {
return false;
}
char potentialEscape = messagePattern.charAt(delimeterStartIndex - 1);
return potentialEscape == ESCAPE_CHAR;
}
private static void deeplyAppendParameter(StringBuilder sbuf, Object o, Map<Object[], Object> seenMap) {
if (o == null) {
sbuf.append("null");
return;
}
if (!o.getClass().isArray()) {
safeObjectAppend(sbuf, o);
} else {
// check for primitive array types because they
// unfortunately cannot be cast to Object[]
if (o instanceof boolean[]) {
booleanArrayAppend(sbuf, (boolean[]) o);
} else if (o instanceof byte[]) {
byteArrayAppend(sbuf, (byte[]) o);
} else if (o instanceof char[]) {
charArrayAppend(sbuf, (char[]) o);
} else if (o instanceof short[]) {
shortArrayAppend(sbuf, (short[]) o);
} else if (o instanceof int[]) {
intArrayAppend(sbuf, (int[]) o);
} else if (o instanceof long[]) {
longArrayAppend(sbuf, (long[]) o);
} else if (o instanceof float[]) {
floatArrayAppend(sbuf, (float[]) o);
} else if (o instanceof double[]) {
doubleArrayAppend(sbuf, (double[]) o);
} else {
objectArrayAppend(sbuf, (Object[]) o, seenMap);
}
}
}
private static void safeObjectAppend(StringBuilder sbuf, Object o) {
try {
String oAsString = o.toString();
sbuf.append(oAsString);
} catch (Throwable t) {
Util.report("SLF4J: Failed toString() invocation on an object of type [" + o.getClass().getName() + "]", t);
sbuf.append("[FAILED toString()]");
}
}
private static void objectArrayAppend(StringBuilder sbuf, Object[] a, Map<Object[], Object> seenMap) {
sbuf.append('[');
if (!seenMap.containsKey(a)) {
seenMap.put(a, null);
final int len = a.length;
for (int i = 0; i < len; i++) {
deeplyAppendParameter(sbuf, a[i], seenMap);
if (i != len - 1)
sbuf.append(", ");
}
// allow repeats in siblings
seenMap.remove(a);
} else {
sbuf.append("...");
}
sbuf.append(']');
}
private static void booleanArrayAppend(StringBuilder sbuf, boolean[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void byteArrayAppend(StringBuilder sbuf, byte[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void charArrayAppend(StringBuilder sbuf, char[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void shortArrayAppend(StringBuilder sbuf, short[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void intArrayAppend(StringBuilder sbuf, int[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void longArrayAppend(StringBuilder sbuf, long[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void floatArrayAppend(StringBuilder sbuf, float[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
private static void doubleArrayAppend(StringBuilder sbuf, double[] a) {
sbuf.append('[');
final int len = a.length;
for (int i = 0; i < len; i++) {
sbuf.append(a[i]);
if (i != len - 1)
sbuf.append(", ");
}
sbuf.append(']');
}
}
public static void main(String[] args) {
System.out.println(format("第一个{}，第二个{}", "a", "b"));
}
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