Android字符串格式化开源库phrase介绍

作者:北京诚信汇发物流有限公司  来源:www.cxhfwL.com  发布时间:2017-09-03 12:42:56
Android字符串格式化开源库phrase介绍

在上一篇博客Android通过String.format格式化(动态改变)字符串资源的显示内容中介绍了通过String.format来格式化string.xml文件中的字符串,本文介绍一个可以实现同样功能的开源库phrase,相比于String.format,通过phrase格式化字符串代码更具可读性。


一、phrase项目介绍:

1、源码:phrase项目的源代码很简单,采集软件,里面总共只有一个类:Phrase.java,代码如下:

/* * Copyright (C) 2013 Square, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package com.uperone.stringformat; import java.util.HashMap; import java.util.HashSet; import java.util.Map; import java.util.Set; import android.app.Fragment; import android.content.Context; import android.content.res.Resources; import android.text.SpannableStringBuilder; import android.view.View; /** * A fluent API for formatting Strings. Canonical usage: * * CharSequence formatted = Phrase.from("Hi {first_name}, you are {age} years old.") * .put("first_name", firstName) * .put("age", age) * .format(); * * *
  • Surround keys with curly braces; use two {{ to escape.
  • *
  • Keys start with lowercase letters followed by lowercase letters and underscores.
  • *
  • Spans are preserved, such as simple HTML tags found in strings.xml.
  • *
  • Fails fast on any mismatched keys.
  • * * The constructor parses the original pattern into a doubly-linked list of {@link Token}s. * These tokens do not modify the original pattern, thus preserving any spans. *

    * The {@link #format()} method iterates over the tokens, replacing text as it iterates. The * doubly-linked list allows each token to ask its predecessor for the expanded length. */ public final class Phrase { /** The unmodified original pattern. */ private final CharSequence pattern; /** All keys parsed from the original pattern, sans braces. */ private final Set keys = new HashSet(); private final Map keysToValues = new HashMap(); /** Cached result after replacing all keys with corresponding values. */ private CharSequence formatted; /** The constructor parses the original pattern into this doubly-linked list of tokens. */ private Token head; /** When parsing, this is the current character. */ private char curChar; private int curCharIndex; /** Indicates parsing is complete. */ private static final int EOF = 0; /** * Entry point into this API. * * @throws IllegalArgumentException if pattern contains any syntax errors. */ public static Phrase from(Fragment f, int patternResourceId) { return from(f.getResources(), patternResourceId); } /** * Entry point into this API. * * @throws IllegalArgumentException if pattern contains any syntax errors. */ public static Phrase from(View v, int patternResourceId) { return from(v.getResources(), patternResourceId); } /** * Entry point into this API. * * @throws IllegalArgumentException if pattern contains any syntax errors. */ public static Phrase from(Context c, int patternResourceId) { return from(c.getResources(), patternResourceId); } /** * Entry point into this API. * * @throws IllegalArgumentException if pattern contains any syntax errors. */ public static Phrase from(Resources r, int patternResourceId) { return from(r.getText(patternResourceId)); } /** * Entry point into this API; pattern must be non-null. * * @throws IllegalArgumentException if pattern contains any syntax errors. */ public static Phrase from(CharSequence pattern) { return new Phrase(pattern); } /** * Replaces the given key with a non-null value. You may reuse Phrase instances and replace * keys with new values. * * @throws IllegalArgumentException if the key is not in the pattern. */ public Phrase put(String key, CharSequence value) { if (!keys.contains(key)) { throw new IllegalArgumentException("Invalid key: " + key); } if (value == null) { throw new IllegalArgumentException("Null value for '" + key + "'"); } keysToValues.put(key, value); // Invalidate the cached formatted text. formatted = null; return this; } /** @see #put(String, CharSequence) */ public Phrase put(String key, int value) { if (!keys.contains(key)) { throw new IllegalArgumentException("Invalid key: " + key); } keysToValues.put(key, Integer.toString(value)); // Invalidate the cached formatted text. formatted = null; return this; } /** * Silently ignored if the key is not in the pattern. * * @see #put(String, CharSequence) */ public Phrase putOptional(String key, CharSequence value) { return keys.contains(key) ? put(key, value) : this; } /** @see #put(String, CharSequence) */ public Phrase putOptional(String key, int value) { return keys.contains(key) ? put(key, value) : this; } /** * Returns the text after replacing all keys with values. * * @throws IllegalArgumentException if any keys are not replaced. */ public CharSequence format() { if (formatted == null) { if (!keysToValues.keySet().containsAll(keys)) { Set missingKeys = new HashSet(keys); missingKeys.removeAll(keysToValues.keySet()); throw new IllegalArgumentException("Missing keys: " + missingKeys); } // Copy the original pattern to preserve all spans, such as bold, italic, etc. SpannableStringBuilder sb = new SpannableStringBuilder(pattern); for (Token t = head; t != null; t = t.next) { t.expand(sb, keysToValues); } formatted = sb; } return formatted; } /** * Returns the raw pattern without expanding keys; only useful for debugging. Does not pass * through to {@link #format()} because doing so would drop all spans. */ @Override public String toString() { return pattern.toString(); } private Phrase(CharSequence pattern) { curChar = (pattern.length() > 0) ? pattern.charAt(0) : EOF; this.pattern = pattern; // A hand-coded lexer based on the idioms in "Building Recognizers By Hand". // http://www.antlr2.org/book/byhand.pdf. Token prev = null; Token next; while ((next = token(prev)) != null) { // Creates a doubly-linked list of tokens starting with head. if (head == null) head = next; prev = next; } } /** Returns the next token from the input pattern, or null when finished parsing. */ private Token token(Token prev) { if (curChar == EOF) { return null; } if (curChar == '{') { char nextChar = lookahead(); if (nextChar == '{') { return leftCurlyBracket(prev); } else if (nextChar >= 'a' && nextChar = 'a' && curChar

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