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思考题解答:两个策略都 supports 同一 URL 时怎么办?
解决方案:优先级机制
优势:
1.确定性:多个策略匹配时,总是选择优先级最高的
2.灵活性:可动态调整策略优先级
3.可扩展性:新增策略只需实现接口并设置合适的优先级
4.健壮性:总有默认策略兜底,不会返回 null
main
YuWeixia 1 month ago
parent
commit
e300412c66
  1. 70
      w10/AnalyzeCommand.java
  2. 45
      w10/ArticleRepository.java
  3. 14
      w10/CrawlStrategy.java

70
w10/AnalyzeCommand.java

@ -0,0 +1,70 @@
package com.example.datacollect.command;
import com.example.datacollect.model.Article;
import com.example.datacollect.repository.ArticleRepository;
import com.example.datacollect.strategy.CrawlStrategy;
import com.example.datacollect.strategy.StrategyFactory;
import com.example.datacollect.view.ConsoleView;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import java.util.List;
public class AnalyzeCommand implements Command {
private final ConsoleView view;
private final StrategyFactory strategyFactory;
public AnalyzeCommand(ConsoleView view, StrategyFactory strategyFactory) {
this.view = view;
this.strategyFactory = strategyFactory;
}
@Override
public String getName() {
return "analyze";
}
@Override
public void execute(String[] args, ArticleRepository repository) {
if (args.length < 2) {
view.printError("Usage: analyze <url>");
return;
}
String url = args[1];
CrawlStrategy strategy = strategyFactory.getStrategy(url);
if (strategy == null) {
view.printError("No strategy found for: " + url);
return;
}
try {
view.printInfo("Analyzing: " + url);
view.printInfo("Using strategy: " + strategy.getClass().getSimpleName());
Document doc = Jsoup.connect(url).get();
List<Article> articles = strategy.parse(url, doc);
view.printSuccess("=== Analysis Statistics ===");
view.printSuccess("URL: " + url);
view.printSuccess("Strategy: " + strategy.getClass().getSimpleName());
view.printSuccess("Articles found: " + articles.size());
if (!articles.isEmpty()) {
view.printSuccess("Sample titles:");
int count = Math.min(3, articles.size());
for (int i = 0; i < count; i++) {
view.printSuccess(" - " + articles.get(i).getTitle());
}
if (articles.size() > 3) {
view.printSuccess(" ... and " + (articles.size() - 3) + " more");
}
}
view.printSuccess("Note: Articles were NOT stored in repository");
} catch (Exception e) {
view.printError("Failed to analyze: " + e.getMessage());
}
}
}

45
w10/ArticleRepository.java

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package com.example.datacollect.repository;
import com.example.datacollect.model.Article;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class ArticleRepository {
private final List<Article> articles = new ArrayList<>();
public void add(Article article) {
if (article == null) {
throw new IllegalArgumentException("Article cannot be null");
}
articles.add(article);
}
public void addAll(List<Article> articleList) {
if (articleList == null) {
throw new IllegalArgumentException("Article list cannot be null");
}
for (Article article : articleList) {
if (article == null) {
throw new IllegalArgumentException("Article cannot be null");
}
articles.add(article);
}
}
public List<Article> getAll() {
return Collections.unmodifiableList(articles);
}
public int size() {
return articles.size();
}
public void clear() {
articles.clear();
}
public boolean isEmpty() {
return articles.isEmpty();
}
}

14
w10/CrawlStrategy.java

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package com.example.datacollect.strategy;
import com.example.datacollect.model.Article;
import org.jsoup.nodes.Document;
import java.util.List;
public interface CrawlStrategy {
List<Article> parse(String url, Document doc);
boolean supports(String url);
default int getPriority() {
return 0;
}
}
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