为什么有人会这样做：
function flash($title)
{
$flash = app('App\Http\Flash');
return $flash->message('This is a flash message');
}
对此：
use App\Http\Flash;
function flash($title)
{
$flash = new Flash;
return $flash->message('This is a flash message');
}
在第一种情况下，我们将获得可用的容器实例。
在第二种情况下，我们加载Flash类并在flash方法中实例化它。
我看到有人使用第一种方法，我想知道使用第二种方法是否有任何区别。
答案 0 :(得分：8)
如果您在示例中使用它 - 您将无法获利。但是Laravel容器在这种解决方案中提供了更多的功能，而使用简单的实例化对象无法实现。
package a;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CreationHelper;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.CellRangeAddress;
import objs.I;
import objs.J;
public class Main {
static List<I> listI = new ArrayList<I>();
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
populateLists();
Workbook wb = new HSSFWorkbook();
CreationHelper createHelper = wb.getCreationHelper();
Sheet sheet = wb.createSheet("new sheet");
int absRowNo = 0;
for(int count=0;count<listI.size();count++)
{
I i = listI.get(count);
int size = i.getList().size();
int cellNo = 1;
Row row1 = sheet.createRow(absRowNo);
Cell cell1 = row1.createCell(cellNo);
cell1.setCellValue(i.getA());
sheet.addMergedRegion(new CellRangeAddress(absRowNo, // first row (0-based)
absRowNo + (size - 1), // last row (0-based)
cellNo, // first column (0-based)
cellNo // last column (0-based)
));
cellNo++;
Cell cell2 = row1.createCell(cellNo);
cell2.setCellValue(i.getB());
sheet.addMergedRegion(new CellRangeAddress(absRowNo, // first row (0-based)
absRowNo + (size - 1), // last row (0-based)
cellNo, // first column (0-based)
cellNo // last column (0-based)
));
cellNo++;
Cell cell3 = row1.createCell(cellNo);
cell3.setCellValue(i.getC());
sheet.addMergedRegion(new CellRangeAddress(absRowNo, // first row (0-based)
absRowNo + (size - 1), // last row (0-based)
cellNo, // first column (0-based)
cellNo // last column (0-based)
));
cellNo++;
Cell cell4 = row1.createCell(cellNo);
cell4.setCellValue(i.getC());
sheet.addMergedRegion(new CellRangeAddress(absRowNo, // first row (0-based)
absRowNo + (size - 1), // last row (0-based)
cellNo, // first column (0-based)
cellNo // last column (0-based)
));
cellNo++;
int jx = cellNo;
List<J> listJ = i.getList();
int z = absRowNo;
for (int y = 0; y < listJ.size(); y++) {
J j = (J) listJ.get(y);
Row rowJ;
if (y != 0)
rowJ = sheet.createRow(z);
else
rowJ = row1;
Cell c1 = rowJ.createCell(jx);
c1.setCellValue(j.getA());
Cell c2 = rowJ.createCell(jx + 1);
c2.setCellValue(j.getB());
Cell c3 = rowJ.createCell(jx + 2);
c3.setCellValue(j.getC());
z++;
}
absRowNo = absRowNo+i.getList().size();
}
// Write the output to a file
FileOutputStream fileOut = new FileOutputStream("workbook.xls");
wb.write(fileOut);
fileOut.close();
System.out.println("done");
}
private static void populateLists() {
// TODO Auto-generated method stub
I i1 = new I();
i1.setA("i1a");
i1.setB("i1b");
i1.setC("i1c");
i1.setD("i1d");
J j1 = new J();
j1.setA("j1a");
j1.setB("j1b");
j1.setC("j1c");
J j2 = new J();
j2.setA("j2a");
j2.setB("j2b");
j2.setC("j2c");
J j3 = new J();
j3.setA("j3a");
j3.setB("j3b");
j3.setC("j3c");
List<J> listJ = new ArrayList<J>();
listJ.add(j1);
listJ.add(j2);
listJ.add(j3);
i1.setList(listJ);
I i2 = new I();
i2.setA("i2a");
i2.setB("i2b");
i2.setC("i2c");
i2.setD("i2d");
J j5 = new J();
j5.setA("j5a");
j5.setB("j5b");
j5.setC("j5c");
J j4 = new J();
j4.setA("j4a");
j4.setB("j4b");
j4.setC("j4c");
List<J> listJ2 = new ArrayList<J>();
listJ2.add(j4);
listJ2.add(j5);
i2.setList(listJ2);
listI.add(i1);
listI.add(i2);
}
}
Class I:
package objs;
import java.util.List;
public class I {
String a;
String b;
String c;
String d;
List<J> list;
public String getA() {
return a;
}
public void setA(String a) {
this.a = a;
}
public String getB() {
return b;
}
public void setB(String b) {
this.b = b;
}
public String getC() {
return c;
}
public void setC(String c) {
this.c = c;
}
public String getD() {
return d;
}
public void setD(String d) {
this.d = d;
}
public List<J> getList() {
return list;
}
public void setList(List<J> list) {
this.list = list;
}
}
Class J:
package objs;
public class J {
String a;
String b;
String c;
public String getA() {
return a;
}
public void setA(String a) {
this.a = a;
}
public String getB() {
return b;
}
public void setB(String b) {
this.b = b;
}
public String getC() {
return c;
}
public void setC(String c) {
this.c = c;
}
}
接口作为目标来从容器中解析，而是接收它的实现。）还有很多其他做法...... 您可以在此处阅读更详细的http://laravel.com/docs/5.1/container