http断点续传简单实现（java)

/* Ukphd$3J=  
**SiteFileFetch.java qoU3"8  
*/ 2 YxTMT  
package NetFox; f"5g>[1  
import java.io.*; +Ezgn/bS&  
import java.net.*; 5F $V`kYT  
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public class SiteFileFetch extends Thread { j) vlM+  
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SiteInfoBean siteInfoBean = null; //文件信息Bean 3/6/G}s  
long[] nStartPos; //开始位置 ZU2laqa_  
long[] nEndPos; //结束位置 A2H4k|8  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 g[z.*y/  
long nFileLength; //文件长度  -7]Xjb5  
boolean bFirst = true; //是否第一次取文件 :VA.QrKW  
boolean bStop = false; //停止标志 ~%y@Xsot>  
File tmpFile; //文件下载的临时信息 _GtBP'iN  
DataOutputStream output; //输出到文件的输出流 # '|'r+  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） C'mL&  
public SiteFileFetch(SiteInfoBean bean) throws IOException H}0dd"  
{ u=+q$Q]  
siteInfoBean = bean; F phDF  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); $a;]_Y  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 'Pltn{iq[  
if(tmpFile.exists ()) $ItF])Bj5N  
{ HL{$ ^l#v  
bFirst = false; wdE?SDs  
read_nPos(); %'Xk)-+y  
} &~DTZgY  
else k!XhFWb  
{ [THG4582oB  
nStartPos = new long[bean.getNSplitter()]; l95<QI  
nEndPos = new long[bean.getNSplitter()]; &~sfYW  
} `m~syKz4A  
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} jdqj=Yc  
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public void run() }odV_WT  
{ t` ^Vb-  
//获得文件长度 ,Fqz e/  
//分割文件 pb;")Q'  
//实例FileSplitterFetch {y^3> 7  
//启动FileSplitterFetch线程 =d;Vk  
//等待子线程返回 2YwVU.*>  
try{ y>VcgLIB  
if(bFirst) do/)~9[4\  
{ "E!mva*NU  
nFileLength = getFileSize(); I=DLPgzO9  
if(nFileLength == -1) |PVt}*0"  
{ ztM<J+  
System.err.println("File Length is not known!");  :S %lv  
} -f(/
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else if(nFileLength == -2) 9L eNe}9v  
{ #TJk-1XM*q  
System.err.println("File is not access!"); m@xi0t  
} JQKdW  
else V2&^!#=s  
{ 25{ uz  
for(int i=0;i<nStartPos.length;i++) **_&i!dtL  
{ ")#<y@Rv  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); ak:v3cQR  
} <|6%9@  
for(int i=0;i<nEndPos.length-1;i++) 0&Gl@4oZ"  
{ M++0zh
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nEndPos = nStartPos[i+1]; y&T&1o  
} i^Ut015q%  
nEndPos[nEndPos.length-1] = nFileLength; |KCOfVh?|.  
} "A
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} c$E)P$<j  
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;]D(33)(  
//启动子线程 H6kf K5,  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; D}mL7d1  
for(int i=0;i<nStartPos.length;i++) &wH:aD  
{ QOFvsJ<s  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), {kB `>VS  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), G
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nStartPos,nEndPos,i); | FM }  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); M7}Q=q\9
 
fileSplitterFetch.start(); |!z2oO  
} cL7g}$W$  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), aC=['a>)  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); _cqy`p@"  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", }6zbT-i  
nEndPos = " + nFileLength); %FkLQ+v/<  
// fileSplitterFetch[nPos.length-1].start(); 4n( E;!s  
[W,|kDK  
]TpU"JD  
//等待子线程结束 =C7 khE  
//int count = 0; hXL|22>w<  
//是否结束while循环 U5ZX78>a  
boolean breakWhile = false; qc-,+sn(  
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while(!bStop) z5cYyx r>  
{  .jg0a  
write_nPos(); j.?:Gaab?#  
Utility.sleep(500); D>ef  
breakWhile = true; 2OBfHO~D  
/="HqBI#i  
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for(int i=0;i<nStartPos.length;i++) W.}].7}h  
{ 9t:]  
if(!fileSplitterFetch.bDownOver) BR_TykP  
{ :KE/!]z  
breakWhile = false; +a)E|(cN  
break; 5>0.NiXGf'  
} "cUg>a3  
} "PWl4a&  
if(breakWhile) m)>&ZIXa  
break; T|4snU2M  
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qt?*MyfV  
//count++; ?Hz2-Cn  
//if(count>4) &_-](w`  
// siteStop(); Mhpdaos  
}  $g8}^1  
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System.err.println("文件下载结束！"); wrv5V M}  
} 0&w0aP`Y  
catch(Exception e){e.printStackTrace ();} loOOmHhJ&  
} ISqfU]>[  
(|h:h(C  
jZ9[=?   
//获得文件长度 }uO5q42  
public long getFileSize() ]KK`5Dv|,e  
{ +&v\ /  
int nFileLength = -1; 0{rx.C7|  
try{ hSV@TL  
URL url = new URL(siteInfoBean.getSSiteURL()); 02b6s&L  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 7!4V>O8@  
httpConnection.setRequestProperty("User-Agent","NetFox"); E,"&-`/2v  
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int responseCode=httpConnection.getResponseCode(); Ej
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if(responseCode>=400) n'w,n1z7  
{ v548ysE)  
processErrorCode(responseCode); 5G*II_j  
return -2; //-2 represent access is error P'[<AZ  
} m#@_8
_ M  
H#(<-)j0_  
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String sHeader; DguB  
!q/5yEJ>h  
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for(int i=1;;i++) EQ >t[ &  
{ '1+.t$"/tU  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); Z5)eREi=  
//Utility.log(in.readLine()); ]|oJ)5P  
sHeader=httpConnection.getHeaderFieldKey(i); .[pUuVq]  
if(sHeader!=null) %efGt6&  
{ V|?WF&  
if(sHeader.equals("Content-Length")) Yv\!vW7I  
{ g`Md80*Zfk  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); |r=DBd3  
break; ExhL[1E  
} bKz{wm%
 
} S7sb7c'4 k  
else \9m*(_Qf  
break;
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} <|F-Dd  
} g:~+Pe  
catch(IOException e){e.printStackTrace ();} TipHV;|e  
catch(Exception e){e.printStackTrace ();} Z7#7N wy4  
B
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Utility.log(nFileLength); *@M3p}',M  
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return nFileLength; vDDljQXw4  
} C3"&sdLb$  
~<O,Vs_C/  
{8CWWfHCD  
//保存下载信息（文件指针位置） UzQ$B>f  
private void write_nPos() avNLV  
{ PdE>@0X?M  
try{ FmT `Oa>  
output = new DataOutputStream(new FileOutputStream(tmpFile)); Mtp%co)f  
output.writeInt(nStartPos.length); esq<xuZM4  
for(int i=0;i<nStartPos.length;i++) 6Z
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{ #x)}29%e#  
// output.writeLong(nPos); "'{OIP  
output.writeLong(fileSplitterFetch.nStartPos); $h[Yzl  
output.writeLong(fileSplitterFetch.nEndPos); j$PI,
`  
} TmP8q  
output.close(); /tC9G@Hl  
} ]Z@k|Nw  
catch(IOException e){e.printStackTrace ();} Rc9<^g`  
catch(Exception e){e.printStackTrace ();} mK\aI  
} ;'1Apy  
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//读取保存的下载信息（文件指针位置） y^s1t2]%  
private void read_nPos() n2'|.y}Um:  
{ P;GprJ`l  
try{ qi\n]I  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); rO^xz7K^  
int nCount = input.readInt(); n7iE8SK|k  
nStartPos = new long[nCount]; U$J5r+>  
nEndPos = new long[nCount]; I'A:J  
for(int i=0;i<nStartPos.length;i++) eP|)SU  
{ ,)$Wm-  
nStartPos = input.readLong(); >d%VDjk .  
nEndPos = input.readLong(); Gpu_=9vzv  
} l%PnB )F  
input.close(); %$9:e J?  
} o;;,iHu*  
catch(IOException e){e.printStackTrace ();} (,tHL  
catch(Exception e){e.printStackTrace ();} VkXn8J  
} ~CFMIQ et  
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private void processErrorCode(int nErrorCode) e^frVEV  
{ [=~!w_  
System.err.println("Error Code : " + nErrorCode); iS-K ~qa  
} 4A o{M  
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//停止文件下载 3^~
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public void siteStop() Czh8zB+r  
{ "::9aYd!  
bStop = true; ~d+O/:=K_  
for(int i=0;i<nStartPos.length;i++) .0 X$rX=  
fileSplitterFetch.splitterStop(); lC{L6&T  
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} ?*o;o?5s^  
} qw0~*0}  
//负责部分文件的抓取 fLM.kCD?u  
**FileSplitterFetch.java +$~8)95<B  
*/ |_I[1%&`N  
package NetFox; |Gc&1*$  
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import java.io.*; O3xz|&xY&  
import java.net.*; iiN?\OO^~  
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public class FileSplitterFetch extends Thread { $

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String sURL; //File URL ASq`)Rz  
long nStartPos; //File Snippet Start Position /&6Q)  
long nEndPos; //File Snippet End Position !PI0oh  
int nThreadID; //Thread's ID pXNtN5@FQ  
boolean bDownOver = false; //Downing is over Cz[5Ug'V  
boolean bStop = false; //Stop identical ZIy(<0  
FileAccessI fileAccessI = null; //File Access interface d~/xGB`<  
o@',YF>OQ  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException Xv&%2-V;  
{ w3d\0ub  
this.sURL = sURL; 2<m Q,,j  
this.nStartPos = nStart; 'tSnH&c  
this.nEndPos = nEnd; Q'C4pn@  
nThreadID = id; <G}m#  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 7YD
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} C=s((q*  
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!|(Ao"]
  
public void run() V^WQ6G1  
{ R05T5Q1]A  
while(nStartPos < nEndPos && !bStop) 7_7xL(F/  
{ 9JXhHAxD  
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try{ =xoBC&u  
URL url = new URL(sURL);  HFv?s  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); u{pTva  
httpConnection.setRequestProperty("User-Agent","NetFox"); w&9F>`VET  
String sProperty = "bytes="+nStartPos+"-"; d(\1 }l  
httpConnection.setRequestProperty("RANGE",sProperty); m]e0X*Kg  
Utility.log(sProperty); 7s!AHyZ  
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InputStream input = httpConnection.getInputStream(); % dYI5U89  
//logResponseHead(httpConnection); k|fh\F+$  
|&(H^<+Xp  
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byte[] b = new byte[1024]; Qw}xGlF,  
int nRead; VrudR#q  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) E4hq}  
{ qjzZ}  
nStartPos += fileAccessI.write(b,0,nRead); nHE+p\  
//if(nThreadID == 1) 37~rm  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); j}"]s/= 6  
} <G&WYk%u*  
~V!EtZG$  
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Utility.log("Thread " + nThreadID + " is over!"); Le_CIk 5YL  
bDownOver = true; Od*v5qT;$  
//nPos = fileAccessI.write (b,0,nRead); P mC82"  
} 83B\+]{hD  
catch(Exception e){e.printStackTrace ();} v F]  
} tI `w;e%HN  
} "3v7gtGG  
+6uOg,;  
}@3$)L%n_u  
//打印回应的头信息 :^K~t!@  
public void logResponseHead(HttpURLConnection con) %odw+PhO  
{ xL|?(pQ/BK  
for(int i=1;;i++) z=u~]:.1O  
{ ^NcTWbs-T  
String header=con.getHeaderFieldKey(i); $`ON!,oa  
if(header!=null) FU^Y{sbDg  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); /Ql6]8.P  
Utility.log(header+" : "+con.getHeaderField(header)); VN?<[#ij  
else $B*qNYpPy.  
break; HH+TjX/b  
} bL+sN"Km  
} NuHL5C?To  
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public void splitterStop() NT'Ie]|  
{ Dy98[cL  
bStop = true; \]Kq(k[p  
} b$IY2W<Ln  
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} //VG1@vaVX  
#@IQlqJfY7  
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/* Lqg7D\7j  
**FileAccess.java w6%l8+{R  
*//文件访问(定位，写) 5/*)+  
package NetFox;  <Wp`[S]r  
import java.io.*; 9Y;}JVS  
<?{ SU   
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public class FileAccessI implements Serializable{ ( ?atGFgu  
*4zoAslU1  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 h\Z3yAYd  
RandomAccessFile oSavedFile; hLu&lY  
long nPos; o,iS&U"TC  
4&#vU(-H  
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public FileAccessI() throws IOException $[WN[J  
{ Ufyxw5u5F  
this("",0); Z?v
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} lv*Wnn@k  
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I #Arr#%  
public FileAccessI(String sName,long nPos) throws IOException s9^"wN YQ  
{ *9\oD~2Y  
oSavedFile = new RandomAccessFile(sName,"rw"); #1gTpb+t  
this.nPos = nPos; 9?EY.}~  
oSavedFile.seek(nPos); LPtx|Sx![  
} +# m  
<!$j9)~x  
0]f?Dx/8  
public synchronized int write(byte[] b,int nStart,int nLen) {6REfY c  
{ @`#OC#  
int n = -1; P1M|f4*  
try{ Tom}sFl][  
oSavedFile.write(b,nStart,nLen); GA({ri  
n = nLen; 0b!fWS?,k0  
} qdg= Imx  
catch(IOException e) VKl~oFKXJ  
{ HJ2O@e  
e.printStackTrace (); h5h-}qBA  
} 1"87EP   
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return n; 3/]f4D{MMY  
} -K{\S2  
#$9U=^Z[  
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} C={sE*&dYX  
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B{=,VwaP_  
/* 6'3Ey'drH  
**SiteInfoBean.java l%vhV&  
*/ >B|ofwm*  
package NetFox; ulJ+:zwq$  
/ r`Y'rm  
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public class SiteInfoBean { y0W`E/1t  
?Vb=4B{~  
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private String sSiteURL; //Site's URL @DjG?yLK$  
private String sFilePath; //Saved File's Path YQlpk@X`2  
private String sFileName; //Saved File's Name )[a?J,  
private int nSplitter; //Count of Splited Downloading File M$E8:  
[bQ8A(u  
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public SiteInfoBean() ^+.e5roBKj  
{//nSplitter的缺省值为5 yDl5t-0`  
//default value of nSplitter is 5 4.$hHFqS^5  
this("","","",5); #dXZA>b9  
} ?L.p9o-S0  
#oS  
-F~9f>  
public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) Q'vIeG"o  
{ 2n\i0?RD  
sSiteURL= sURL; J@&$U7t  
sFilePath = sPath; "@):
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sFileName = sName; @5POgQ8  
this.nSplitter = nSpiltter; [K^q:3R  
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} 6'X.[0M  

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k/6Gj}l'o  
public String getSSiteURL() S a#d?:L  
{  Q}`2Y^.  
return sSiteURL; )@};lmPR  
} 9=sMKc%!-  
8wNU2yH+D  
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public void setSSiteURL(String value) _16&K}<  
{ m78MWz]Yo  
sSiteURL = value; ui:>eYv  
} }tg:DG  
Ix l"'Q_z  
~vvQz"  
public String getSFilePath() y0Q/B|&[  
{ xHR+((  
return sFilePath; $T@xnZ  
} :+X2>Lu$FA  
'FvhzGn9Q
 
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public void setSFilePath(String value) %d~9at6-B  
{ gEe W1:AB  
sFilePath = value; ]f+D& qZ B  
} :7AauoI  
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](( >i%%~  
public String getSFileName() &bRxy`ZH  
{ % /wP2O<  
return sFileName; ;gw!;!T  
} f%{ ag  
WG!;,~f>o  
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public void setSFileName(String value) ^?l-YnQqm?  
{ "=0lcbC  
sFileName = value; .$T:n[@  
} Yk*57&QI  
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DG%%]  
public int getNSplitter() 2ucsTh@  
{ APOU&Wd  
return nSplitter; `cTsS  
} ($ 1<Dj:  
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public void setNSplitter(int nCount) `0i}}Zo  
{ 26klW:2*  
nSplitter = nCount; W
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} M`,Z#)Af  
} 3Tte8]0  
#p:jKAc3  
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/* )@&?i.  
**Utility.java d?+oT0pCH  
*/ r:\5/0(  
package NetFox; ff+9(P>*  
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m"> =QP  
public class Utility { 7XI4=O};&%  
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public Utility() i)^ZH#Gp  
{ | 3/p8  
Bv|9{:1%X}  
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} .j$bCKXGx  
3'NL1du  
//线程睡眠 9;WOqBD  
public static void sleep(int nSecond) :FgRe,D  
{ ,0u0 '  
try{ x@RA1&c  
Thread.sleep(nSecond); CjukD%>sde  
} oL/^[TXjH  
catch(Exception e) XjM)/-w  
{ X;a{J
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e.printStackTrace (); A2FU}Ym0=  
} Kgio}y  
} 2n r UE  
H_r'q9@<>  
//日志 ZN]c>w[ )I  
public static void log(String sMsg) >Ti2E+}[M  
{ 
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System.err.println(sMsg); Pj5#G0i%  
} a/`Yh>ou  
|ssIUJ  

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public static void log(int sMsg) (dprY1noC  
{ Zkep7L   
System.err.println(sMsg); :[rKSA]@  
} #$^i x  
} V# %spW  
.*ovIU8  
gd,%H@3  
/* !rqR]nd  
**TestMethod.java eBRP%<=>D  
*/ 2%yJo7f$[  
package NetFox; U@AfRUF&  
w+(wvNmNEK  
NjyIwo0  
public class TestMethod { zjZTar1Re  
(dt_
D  
>43yty\   
public TestMethod() *^5,7}9Qo  
{ ///xx/weblogic60b2_win.exe xa*gQ%+F  
try{ ^W05Z!}  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); ^<Tp-,J$EN  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); G&H"8REm  
SiteFileFetch fileFetch = new SiteFileFetch(bean); QYb?;Z  
fileFetch.start(); e%Xf*64  
} j7 3@Yi%  
catch(Exception e){e.printStackTrace ();} PGhZ`nl  
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} ?YykCJJ ~@  
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odn`%ok  
public static void main(String[] args) qP'g}Pc  
{ %$KO]   
new TestMethod(); L=F
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} *g6o ;c  
} c9@jyq_H?  
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